The compact has a smaller inner diameter for its chain rings allowing it to run smaller chain rings. I tihink it is 110 versus 130… or somethign like that So depending on what you are looking for these are not the same product.
Compact cranks were hotly debated in great detail not long ago. Stronglight makes a set that are a bit lighter than Ultegra and considerably less expensive than FSA. I’ve already purchased two pairs.
Ritchey is producing an OCTALINK compatible alloy crankset that is 600 grams, has a 110bcd and should retail for under $150. This will bolt right onto a Shimano 105 5500 109.5mm BB, and Ultegra 6500 109.5mm BB and a Dura Ace 7700 and 7710 109.5mm BB. FSA and Stronglight both use different spindle interfaces, it is very unlikely that you have either as OEM on your bike.