It looks like you have a View. The cold side is going to have a extra connection feeding the toilet that the hot side won't have. Maybe you can see which is which from that.
Other than that I suggest you buy a 1/2" sharkbite coupling and the 1/2" sharkbite tool that lets you release the tube from a fitting if need be. Do one side, you have a 50-50 chance of getting right. In any case you'll know hot and cold at that point and, if wrong you can use the release tool to disconnect and fix.
Randy - Manhattan, Kansas
2015 Vista 27N
2016 Honda HR-V