They're all too young to tell, a red foot is sexually mature when 5-8 years old, or when they grow up to 8".
If I were to take a guess just based on what I see in the photos, the first looks a bit like a female, and the second sorta looks like a male.
Tho be aware, since sometimes you can think your tortoise is a girl when it turns out to be a guy, or vise versa.
If you're impatient on waiting, you could try to soak both of them and see if one may flag you (when the male shows off its penis), though it's not very common when the tortoise is sexually immature (it happens, just not often).
Behavior wise, when the tortoises start to mature the male can show signs of aggression or impatience to other tortoises (flagging, nipping, circling other torts or bumping into them repeatedly). The female mostly stays more calm and doesn't show aggression unless if she feels threatened.
Here's a chart to show gender development in young tortoises. The chart was made in referance to Russian torts, but it could be applied to red foots as well.