Bowl Size

In terms of how much they can store then yes. You can get a bowl that fill up a ton to pass around (not a good idea with a bong, someone is bound to drop it) or you can get a smaller piece that fills less. Or you can buy two piece to use whenever you feel like it. However there are different sizes in the hole (carb area) of a bong. So one piece might be too small or two large to fit depending on the bong (unfortunately there isn't a universal size or size range. I might be wrong on the size range, But I've seen them all over the place) To find the right piece you need to measure your old one out or measure your bong's carb hole. P.S. I'm not sure if it's called a carb hole or not, I'm just trying to give you and idea of what I'm talking about. Also if you buy a piece thats too small to fit in your bong, I've had friends use rubber stoppers with sized holes in them to get there new piece to fit in there bong (it works well but it looks ugly). You can pick these up at your local hardware store.

 

For a glass on glass bong, the most common sizes are 14.4 MM and 18.8 MM. There is also a special brand called Zumo made by RooR that uses 22.1MM fittings.

 

9mm and 12mm are pretty standard for bongs with rubber o-rings. get a tapered one with a fatty o-ring and youll have no problems.