Von Mises and Tresca's yield criterion

I have a fundamental question.

We ahve read that, physically  the Von Mises yield criterion is arrived based on the assumption / experimental observations that for a multi-axial state of stress, yielding starts when the maximum distortional / shear energy in uni-axial / simple tension.

whereas;

Tresca’s yield criterion is based on the assumption / experimental observation that yielding starts when the maximum shear stress in the material equals the maximum shear stress at yielding in simple tension.

Now, I want to know is:

1) are both Von Mises and Teresca's yield criterion (which are for multi axial state of stress) based on experiemntal observations?

Which one is more precise?

If they are both arrived based on experimental observations, how can there be 2 (different) sets of experiemntal observations for a given outcome?

Sorry about asking this (which might sound stupid) question.