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impact driver doesn't drill holes, but has far higher torque and less likely to slip off a screw head.
An impact driver will drill up to ~ 10mm holes fine (in wood not any other material) but you need to buy 1/4" hex shank bits, you can buy a chuck that fits but what's the point. Above 10mm the impact will activate and the drill bit is likely to shatter. They actually do a decent job of drilling pilot holes etc as the unloaded speed of an impact driver is much higher than most handheld drills.
A combi drill is capable of producing much higher torque than an impact but because of the way it is generated Newton's 3rd law comes into play (every action has its equal and opposite reaction) meaning that you have to counter the rotation produced with your hand. In worse case scenario this can result in breaking your wrist, this mostly happens if a drill is being held in one hand and catches. Impacts generate their torque by a hammer impacting an anvil in the gear box this makes them much more controllable also as a side effect this means you're less likely to round heads.
Bobbo-
These are fantastic for drilling joists with an impact driver. Honestly a game changing purchase, lol.
https://www.toolstation.com/dewalt-tri-flute-spade-bit-extreme/p77501
Nef
my "I don't know what I'm talking about" summary
electric screwdriver will replace you putting in a screw by hand with a screwdriver
drill will drill holes and do a decent job of putting screws in
impact driver doesn't drill holes, but has far higher torque and less likely to slip off a screw head. So if you're putting a lot of screws into a wall then you're going to get through it more quickly and without rounding out a bunch of heads