my wife's gonna gm a 1-on-1 campaign of pathfinder 1e for me for spanish practice/fun combo reasons and i am learning that there's a lot of very basic 3.5e d&d/1e pathfinder rules i was not aware of before now (admittedly, i never played either but)

for example that the encumbrance rules in most circumstances are "dwbi, just apply your armor penalties", or that 2-handed weapons get one and a half times your strength modifier as a bonus, or that when you do e.g. double damage, you roll the damage dice twice rather than just, rolling once and doubling the result.