in board
 

Bit of a newbie question but is an inboard battery a stick pack?

Hard to say, whats the context? Inboard is more of a boat term such as inboard or outboard motor.

Inboard could just mean it is inside the body/chassis or maybe like on some Tamiya kits where the battery slides inside a hole in the chassis. These are often stick packs like this Mini chassis

http://rclazy.com/wp-content/uploads/2009/05/m05.jpg

Im thinking of the VBC off road car but have stick packs and website says it takes inboard shorty and saddle packs so wantto know if I need some new batteries too

Saddles will fit where a stick pack would as they are essentially 2 packs half size. Usually they go side by side. A stick pack prob won't fit if it says saddle packs. Shorty are as described. Shorter and wider so are size specific