Check out Wikkipedia which explains it better but
Thee Virginia plan was a plan to give the largest states (Virginia at the time) more votes than the smaller states. Needless to say it was widely supported by large states, and heavily contested by small states that were afraid they would get bulldozed by large states.
The New Jersey Plan was the alternative (each state gets one vote).
In the end the Conneticut compromise was chosen...which gave each state one vote (Senate), but made a second tier of government (House of Representatives) which represented the size of each state.