The Presbyterians and the Reformed Churches, along with many, but not all, Baptist denominations believe in Calvinism
this is a system of beliefs that have at the core the total depravity of natural man and that Grace from God is irresistible. The emphasis is on the sovereignty of God, which all Christians believe in, but not all all Christians interpret in the same way as Calvinists
Actually as most Reformed will tell you, they hold strongly to the teachings of Apostle Paul, as laid out in Romans 8-10. That is where Total Depravity, Unconditional Election, Limited Atonement(Jacob have I loved, Esau have I hated), Irresistible Grace, and Preservation of the Saints can be found.
So it is not that we are following the man Calvin, or even the Apostle Paul, but Jesus who also says these things throughout the Gospels, John being the one most of these can also be found in)
However, Most Baptists will tell you they are Only Four Point Calvinists until you debate what Limited Atonement means.
And What the Reformed called "Preservation of the Saints" in the Baptist Traditions is known as "Once Saved Always Saved"
Also a major difference worth noting, Presbyterians don't generally do adult Baptisms, prefering to Baptize Infants and dedicate them to the Lord, whereas to the Baptist, Following Christ in every step means starting your journey with a Baptism.
And for the Baptist, while others may sprinkle or have water dropped on their forehead in the shape of a cross, it's not their way, the Baptist way is to fully Immerse in water, as they maintain rightly the word "Baptizo" in Greek means. Christ was Bapitzo'd in the Jordan River.
Now Baptists have different ways of doing this, most Baptists be they reformed or Southern or of many other denomiations have a Baptismal Pool in the Sanctuary for Baptisms to be done in. Most are raised up and behind the Choir loft, though I have seen one in the floor behind the stage(There was no choir loft in that church, they were above us.) There are though some Baptists that will take their members down the nearest body of water(lake, river, the Ocean, a creek, what-have-you) and try to do it as best they can as they can see Jesus was Baptized by John.
Just thoughts I wanted to point out.
Oh and there are amongst the more liberal Baptists (Such as the NBC/ABC and liberal SBC) groups that are Arminians (Semi and Full) not all of them are but some.They can even found in some conservative groups as Baptists don't have any political body that governs things, they believe in total autonomy of Church Discipline, in fact the only form of Church Discipline that can be done, is to dis-fellowship a church from a Convention(Takes a majority vote), or an individual member from his church, but that has to be done by the church(according to their own governing rules they establish). Sadly this means that a Church with a heretical Preacher can still keep the name Baptist, but will have to lose the Membership and logo from whatever group they were a part of.
Presbyterians and most Reformed have a more solid body politic that can actually fix problems, and deal with people or teachings on a wider level. And the Presbyters can caste a preacher out, so he can longer be called a Presbyterian Minister. He may be able to go to another denomination.
Then there's the debate on the Sacraments, Every Baptist group I've known has taken the "Symbolic only" view. I see that the Reformed and maybe some Presbyterians have a different view, one I'm not fully sure on "The Spiritual View". I do know the PCA view is close to the Baptist view.