First time poster but long time lurker so don't be too hard on me. But I will give you an answer as an O-Line coach.
Gap Schemes: Are typical plays Power, Counter, and Trap. First Power, play side linemen block down (each takes the Gap toward the center, the center takes the backside 'A' gap) and creates a wall, then a back kicks out the last man on the line, this can be the Fullback, H-Back, a motioning WR etc. Back side Guard will pull and wrap around the wall to the first linebacker he sees, backside Tackle will step to the Center to help fill for the puller. Next Counter, play side linemen block down (just like power), now the back side Guard kicks out, Fullback, H-Back wraps up the wall, backside Tackle steps to the Center to help fill for the puller. On Counter Trey the backside Guard still kicks out the backside Tackle will wrap and the Fullback, H-Back will fill for the pulling linemen. On Trap we turn loose the first down lineman past the Guard, Center and play side Guard will block down, play side Tackle will block the first linebacker inside, backside Guard will pull and kick out the free D-Lineman.
Gap Schemes in a nutshell.
Zone Schemes are different and are more based on the running back reading the right crease to get vertical. A running back who does not read the right crease will make the O-Line look like a bunch of chumps.
This post already is rather long so if you want I can explain Zone Schemes later.
Grappler