Glacier: snow or ice buildup that does not melt before the next winter comes. Occurred during ice-age periods, and occurs now
Ice sheet or ice cap: glacier large enough that it is not confined by topography. Regional to near continent size glacier; spreads outward from ice accumulation zones.
Sea Ice: Occurred during ice-age periods; and occurs now.
Alpine glaciers: Occur in mountains and valleys
Cirque glacier; tightly confined by topography near zone of snow compaction
Valley glacier; flows down valleys
when valley glaciers discharge ice into broad, flowing lobes at the base of mountains