Not going to do all of the research for you...but here's something to get you started
SSRI: selective serotonin reuptake inhibitors.
Translation: helps prevent serotonin from being reuptook (?), resulting in higher serotonin levels
Includes fluoxetine (Prozac), setraline (Zoloft), citalopram (Celexa) and a few other common antidepressants.
MAOI: monoamine oxidase inhibitors.
Translation: inhibits monoamine oxidase.
Some older antidepressants were of this type. Noted for having severe side effects, severe and even fatal interactions with many other psych AND non-psych medications, and for requiring dietary restrictions (notably, a low-tyramine diet). So it's often prescribed as a last-resort when all else fails.