I tend to use the nationals patterns as a good analogy. The team pattern is always side to side. Transition management aside, there's a specific spot down lane you MUST get the ball to regardless of how you're playing the lanes or what balls you're using, you just have to get it to a certain breakpoint. Whether you're playing dead up 5 or crossing 5th arrow, you've gotta get it to the same couple boards down lane to get the ball to the pocket, that's side to side. The Doubles and Singles pattern is more front to back, you can play around a lot more with covers and surfaces and angles and ball shapes because it doesn't matter nearly as much where you get the ball to down lane as how you're getting it there. You can play 5 as your breakpoint if you're going straighter with a lot of surface, or if you're playing tighter with shiny stuff, you can play in as far as 12, you just have to have the right matchup, shape, and have to be rolling it the right way to get it to act right, that's front to back.
There's still no easy way to explain it. With side to side, generally you have free shape, you just have to get it to the right spot down lane, with front to back, you have to create the shape yourself, but you have a lot more freedom with laneplay. At least that's how I see it and treat it myself . . and it's not necessarily short patterns or flat patterns are side to side and longer or heavier patterns are front to back, some heavier patterns like Badger can be extremely side to side AND front to back at the same time. You have to get it to a certain point down lane AND be doing the right things to make the ball shape up right at the end of the pattern. Shorter patterns do tend to be side to side more often because the ball is going to hook, you just need to get it to the right spot, BUT in certain cases they're so short and there's so much friction that the ball will burn up and look like you're bowling on a flood unless you get it acting right yourself.
