system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Baptist vs. Methodist vs. Lutheran vs. Presbyterian, etc.

I mean besides the general "Baptists tend to be more conservative" thing. What are the actual official differences in beliefs? They seem pretty interchangeable.
gpt
Okay, short answer is : Doctrine.

There is a continuum for religious doctrine that runs roughly from Arminian to Reformed. This has to do with how they believe we react to God. Armenians believe we continually choose to go to heaven or hell, and can decide to be with God or to stray at any point. Reformed Calvianism is the other extreme, that God chose whom he will send to heaven and hell, and only died for certain people for his own reasons. There is an acronym for this called TULIP that details this doctrine

Methodists are closer to arminian

Presbyterians are closer to Reformed/Calvanism. They believe in infant baptism, (because God picked you anyway) Baptists are horrified by this because you didn't make the choice to turn from your sins and follow God via faith in his plan for salvation. 

Baptists are very broad doctrinally and are governed by the southern baptist convention, believing in baptism as a demonstration of salvation. They are relatively centrally located on the aforementioned continuum. evangelism is their focus, and they concentrate on spreading the gospel (the good news that Jesus died for your sins so you can go to heaven.

Lutheran is in line with the reactionary teachings of Martin Luther. All of these denominations believe you go to heaven by faith, not by what you do (i.e. baptism, obedience, communion), but the lutherans are focused on this; and an individual faith with God. as such, they lie in the middle territory overlapping much of the Baptist beliefs. Salvation is for all, which is contrary to TULIP presbyterians.

One branch is not necessarily more conservative than the other. United Methodists are VERY liberal, and primitive Baptists are weapons grade conservative, but and evangelical methodist is more conservative than an American Baptist Church

Conservative -> believes the bible

Liberal -> Bible's a nice guideline, not necessarily all real or literal


The real difference you should know with protestants is evangelical vs. mainline

Evangelicals (Some baptists, non-denominational) tend to be more theologically conservative, but less formal in church settings. they tend to have "megachurches" with rock bands and focus on spreading the gospel. These churches are maintaining numbers and even growing in some areas of the country, which you would expect since they are always telling people about Jesus.

Mainlines  (lutherans, methodists, presbyterians) tend to be more theologically liberal, but more stodgy in execution. they focus on church history, sing hymns and you'd rarely catch jeans in a Sunday service. They are dying demographically, as they are predominately old and white. They don't focus on outreach for spreading the word, but are often active in community service.