They operate as straight forwardly as they are worded.
Auto lift = automatic lift of the throttle on gear change (for cars that require it...say, if you didn't have a clutch pedal..or if you use auto clutch you may use this as well) A lot of cars require a lift on upshifts...gears cannot always be forced with foot to floor. If you're using clutch, this probably comes naturally.
Auto blib = an automatic throttle "blip" on downshifts (keeps from blocking the rears on downshifts, balance of the car, etc) Some cars (especially older cars...anything with H pattern - mostly...etc) require a blip on downshifts. (ie...rev matching)
If you like to drive the cars "as realistically as possible" you'll want to turn both of those off. Not sure they always have an effect when on but I don't test that...not something I use.