One is unintentional homicide, while the other is murder.
While all sin is sin, the breaking of God's law, and to break even just one means you are a law-breaker along with profligate sinners, (James 2:10,11) yet Scripture makes manifest that there are different degrees of both wickedness and of guilt.
Thus there were church-going Corinthians who were carnal in the sense of being immature as manifested
, "For ye are yet carnal: for whereas there is among you envying, and strife, and divisions, are ye not carnal, and walk as men?" (1 Corinthians 3:3)
Then there were those who were to be put out of the church by them:
B
ut now I have written unto you not to keep company, if any man that is called a brother be a fornicator, or covetous, or an idolater, or a railer, or a drunkard, or an extortioner; with such an one no not to eat. For what have I to do to judge them also that are without? do not ye judge them that are within? (1 Corinthians 5:11-12)
This difference is also inferred later,
For I fear, lest, when I come, I shall not find you such as I would, and that I shall be found unto you such as ye would not: lest there be debates, envyings, wraths, strifes, backbitings, whisperings, swellings, tumults:
And lest, when I come again, my God will humble me among you, and that I shall bewail many which have sinned already, and have not repented of the uncleanness and fornication and lasciviousness which they have committed. (2 Corinthians 12:20-21)
Sodom and and Gomorrah were not destroyed because they sometimes engaged in foolish jesting or had respect of persons, which is sin, (James 2:9) but because the cry of their iniquity was great, (Genesis 18:20) both in weight and degree, even to being given to fornication and committing the abomination of rampant homosexual fornication. (Ezekiel 16:49.,50, Jude 1:7)
Yet the guilt was greater for those who saw such a level of light and grace that even Sodom would have repented if they were given the same.
And thou, Capernaum, which art exalted unto heaven, shalt be brought down to hell: for if the mighty works, which have been done in thee, had been done in Sodom, it would have remained until this day. (Matthew 11:23)
Likewise the Lord told the religious leaders who sat in the seat of Moses and were thus more accountable, that they
"shall receive the greater damnation" (Matthew 23:14).
In contrast,
But he that knew not, and did commit things worthy of stripes, shall be beaten with few stripes. For unto whomsoever much is given, of him shall be much required: and to whom men have committed much, of him they will ask the more. (Luke 12:48)
For despite the denial of heretics, there are indeed sins of ignorance:
If a soul shall sin through ignorance against any of the commandments of the Lord concerning things which ought not to be done, and shall do against any of them: (Leviticus 4:2)
But unlike such sins as adultery, (Leviticus 22) such did not refer to capital offenses. And thus Paul, who ignorantly thought he was serving God by cleansing the land of the followers of the "sect of the Nazarene," (Acts 24:5) received mercy:
Who was before a blasphemer, and a persecutor, and injurious: but I obtained mercy, because I did it ignorantly in unbelief. (1 Timothy 1:13) Thus he could profess,
Men and brethren, I have lived in all good conscience before God until this day. (Acts 23:1)
Also, one can indeed can sin out of weakness, not with full consent of the will which is rebellion, and which is seen in contrast to struggling against sin. The latter is what Paul referred to in Rm. 7,
For the good that I would I do not: but the evil which I would not, that I do. (Romans 7:19)
And which Hebrews 12:1 refers to:
"Wherefore seeing we also are compassed about with so great a cloud of witnesses, let us lay aside every weight, and the sin which doth so easily beset us, and let us run with patience the race that is set before us,..." (Hebrews 12:1)
There is a difference between a halfhearted commitment to Christ and that of the whole heart, as well as a difference btwn someone struggling with giving up smoking, or overcoming a quick temper, or being envious, etc., which are sinful, and that of willfully practicing such sins as adultery.
And while one can sin will-fully by giving into the flesh, yet if they do not repent when convicted of their ways while they can, they will end up having departed from the Lord. Sinning willfully thus sees this warning:
For if we sin wilfully after that we have received the knowledge of the truth, there remaineth no more sacrifice for sins, But a certain fearful looking for of judgment and fiery indignation, which shall devour the adversaries. He that despised Moses' law died without mercy under two or three witnesses: Of how much sorer punishment, suppose ye, shall he be thought worthy, who hath trodden under foot the Son of God, and hath counted the blood of the covenant, wherewith he was sanctified, an unholy thing, and hath done despite unto the Spirit of grace? For we know him that hath said, Vengeance belongeth unto me, I will recompense, saith the Lord. And again, The Lord shall judge his people. It is a fearful thing to fall into the hands of the living God. (Hebrews 10:26-31)
Now the just shall live by faith: but if any man draw back, my soul shall have no pleasure in him. But we are not of them who draw back unto perdition; but of them that believe to the saving of the soul. (Hebrews 10:38-39; cf. Hebrews 3:12; Galatians 5:1-5)
Take heed, brethren, lest there be in any of you an evil heart of unbelief, in departing from the living God. (Hebrews 3:12)
And thus even though David sinned, he could profess,
For I have kept the ways of the Lord, and have not wickedly departed from my God. (2 Samuel 22:22)
David sinned against the Lord via adultery and 1st degree murder, yet since he repented immediately when convicted of his sins then he could profess that he never
wickedly departed. And which David the psalmist prayed against saying,
Keep back thy servant also from presumptuous sins; let them not have dominion over me: then shall I be upright, and I shall be innocent from the great transgression. (Psalms 19:13)
Which would be to die in final apostasy, the sin unto death.
And those who imagine they no longer sin based upon their specious wresting of Scriptures such as excludes mistreatment of others as being sin, or that the only reality is what one positionally is in Christ, are deceived and being deceived, against which 1 John 1:10 and 2 Peter 3:16 warns.