Okay, let's start with uplift. As the name suggests, this is a term that refers to the "uplifting" of land forms in relation to the Earth's surface, usually resulting in an increase in elevation. Uplift may be produced by any of the following three methods:
1) Orogenic uplift is when two tectonic plates converge together, and pile up crustal material between them, resulting in huge mountain ranges. The Himalayan Mountains were and are being formed this way.
2) Isolithic uplift occurs when earthen material is eroded from around a landform, causing it to appear to have risen to new heights in elevation.
3) Coral islands are produced by mass pilings of coral, which cement themselves together in the form of reefs, and then outright islands.
Subsidence is the exact opposite of uplift, the prefix "sub-" indicating below, or beneath. This is when land forms sink to lower elevations than they previously had. Dissolution of limestone (dissolving of limestone), mining, natural gas extraction, and ground water lowering all produce examples of subsidence, where land will sink lower, incapable of sustaining it's previous elevation.