There are two mufflers I'm looking at. Dynomax Super Turbo Part #17746 and
17736. These are the differences.

17746 inlet center, outlet offset, case length 20 inches.

17736 inlet offset, outlet offset, case length 14 inches.

What will be the difference between these two? Does one flow better?

 

No... when you run your exhaust pipe, its not as wide as a muffler. The "inlets and outlets" are the connecting points for the rest of your exhaust system. If one is offset, that just means that your exhaust piping won't connect to the center of the muffler (end-wise) but rather 2 or 3 inches to the left/right of the center point.

___________

center
____________

____________
offset

____________

Essentially, the only advantages to an offset inlet or outlet is for application. On a Toyota truck, you have a lot of playaround room and can pretty much weld up a janky exhaust out of galvanized fence post cornered around garage objects (no lie, been there). But a compact car like a 1995 Camaro actually has little room to work with on muffler location and exhaust pipe routing and muffler choice is key to prevent poor ground clearance, heat radiation to surrounding parts, etc.

My advice?
Look at your stock muffler. Its a bit unusual because its a long cylinder and the Dynomax is, more than likely, gonna be a very oval-shaped cylinder. FInd the "end" of your cylindrical, stock muffler and measure from the center point to where the exhaust piping enters/exits on both ends.