You can locate the different account types by scrolling through the Market Watch pairs/instruments. If you can't see them/any, right-click on a pair/instrument and click "Show All".
Standard Pairs $7 Commission Majors pairs have a medium spread.
Pro Pairs* (.pro) $8 Commission Majors pairs have a smaller spread.
Var Pairs (.var) $0 Commission No Commission and higher spreads.
Mini Pairs (.mini) $1 Commission Smaller lot sizes (1 lot = 1000).
Big Pairs (.big) $10 Commission Larger contract sizes, depending on the pair selected.
*The above commission stated for Pro pairs is excluding XAUUSD.pro which holds a commission fee of $10, as it falls under the Metals category.
Different account types are only available for Forex and certain other symbols.