Ok, just change God's Word, to get your point across. If you cannot see the difference, then take off those rose colored human theological glasses.
No words are omitted in Luke 21. The people there, at the Temple, asked some questions and got different answers than the disciples did.
The people getting the answers are the disciples.
Not a huge difference in the answers here.
Luke 21
8 And he said, Take heed that ye be not deceived: for many shall come in my name, saying, I am Christ; and the time draweth near: go ye not therefore after them.
9 But when ye shall hear of wars and commotions, be not terrified: for these things must first come to pass; but the end is not by and by.
10 Then said he unto them, Nation shall rise against nation, and kingdom against kingdom
11 And great earthquakes shall be in divers places, and famines, and pestilences; and fearful sights and great signs shall there be from heaven.
Mathew 24
4 And Jesus answered and said unto them, Take heed that no man deceive you.
5 For many shall come in my name, saying, I am Christ; and shall deceive many.
6 And ye shall hear of wars and rumours of wars: see that ye be not troubled: for all these things must come to pass, but the end is not yet.
7 For nation shall rise against nation, and kingdom against kingdom: and there shall be famines, and pestilences, and earthquakes, in divers places.
8 All these are the beginning of sorrows.
Mark 13
5 And Jesus answering them began to say, Take heed lest any man deceive you:
6 For many shall come in my name, saying, I am Christ; and shall deceive many.
7 And when ye shall hear of wars and rumours of wars, be ye not troubled: for such things must needs be; but the end shall not be yet.
8 For nation shall rise against nation, and kingdom against kingdom: and there shall be earthquakes in divers places, and there shall be famines and troubles: these are the beginnings of sorrows.