Download format from website vs app

I noticed today a difference in the file format when I download in the Mac app vs the website. The app downloads a much larger file in the .tcx format. I import the files into Golden Cheetah and have not noticed anything different between the two. Any info on what else is include in the .tcx which makes it significantly larger? Just curious.

Right now, I prefer the .tcx file simply because the the name includes the date. I have to manually rename the .fit files because GC can’t handle two files called “” for example.

Aren’t tcx files plain text and fit files binary ? You can open up the tcx in a text editor and check all the info in it. Fit files need a special program. If Memory serves something like “fit file repair tool” can be used fix/edit fit files.

Noted, thanks.