How do they tell who is Hutu or Tutsi?

Generally only by ID, as Ethnicity was registered with officials. However supposedly, according to the racial categorisation through Belgium's colonisation, the Tutsi were apparently lighter skinned, had slimmer noses and were in general taller than Hutu. How this was possible to differentiate when they are all Rwandan and therefore originate most likely from this area is beyond me!

same way asians differentiate each other

Generally

Tutsi - Taller and thinner

Hutu - Shorter and broader

Of course there are also half Hutu/Tutsi as well!

Its that man again!!

There wasn't really any physical characteristics that you could know for certain. So obviously it was mainly body language, which is to say tutsis would be afraid of being found out by hutus and this would be very apparent in their body language. Impossible to hide really.

I'm sure many tutsis escaped by pretending to be hutus but they must have been incredible liars and been incredibly courageous.

And no doubt there were many hutus who were killed just cause they thought they were acting suspicious or what have you.

The Hutus wear red and the Tutsi wear blue.

[deleted]