The Pilgrims trailed at half-time in the National League U19 Alliance encounter at Boston Town's DWB Stadium, but Vince's second half free-kick preserved a point.
The sides will meet again next Wednesday in a quickfire mid-season double-header in Division H.
Boston (4-3-3): Harry Payne; James Gordon, Jack Withers, Bailey Forth, Callum Rodger; Peter Evison (Jack Brown 60), Harry Vince, Jordan Tate; George Hobbins (Oli Drummond 86), Liam Adams, Haydn Havard. Subs (not used): Jenson Ball, Connor Stocks, Arkadiusz Michalczyk.