Starfinder What are the big mechanical differences from Pathfinder 1e?

[Voadam]

Thanks to Humble Bundle and a bunch of charity bundles I have a lot of Starfinder PDFs including a bunch of the big Paizo books, a couple adventure paths and adventures, and a bunch of 3rd party Starfinder stuff.

I played and DM'd a bunch of Pathfinder 1e, but I have not gone though most any of Starfinder stuff yet besides some surface skims for things like monsters to use in Pathfinder and some flavor ideas for use in a non-Starfinder game. But a player in my face to face group (the current DM) has been jonesing for playing in a full sci-fi game and I feel I might be up for running a Pathfinder in space adventure (one-shot or campaign) since I have Starfinder modules and APs.

What are the big mechanical differences from PF1?

My second hand general understanding is that it is basically Pathfinder in space (far future Golarion) with different classes, big difference being only having six levels of spells?

 

[Arakhor]

I think that the biggest differences are:

Armour Class is split into Energy (EAC) and Kinetic (KAC) Armour Class
There are fewer skills (Craft, in particular being subsumed) and fewer bonus types
Characters have both Hit Points and Stamina, with Stamina being taken first and able to be replaced after a ten-minute rest, and healing spells only able to restore Hit Points
There are six levels of spells, which feature a certain amount of down-casting (if you have the Flight spell at 1st-level, it works as featherfall, but if you have it at 3rd, you can use it as featherfall, levitate or fly)
There are no iterative attacks, but everyone can attack twice as a combat action

 

[Alzrius]

I'm not sure I'd call it one of the "big" mechanical differences, but the way that weapons, armor, and other magic items are classified under the system has changed. While they still use an in-character pricing system, those items all have "levels" which serve (similar to Challenge Ratings) as indicators for what level PCs they're appropriate for (though, like CRs, this is a soft system that doesn't have mechanical enforcement; you can give PCs items that are level-inappropriate the same way you can throw high- or low-CR monsters at them).