Acrylic sealer vs. varnish

I'm new to sealing paintings so I have no clue if there is a difference. But I have started painting on shoes so I have to seal it.

I used a glossy varnish and then put a matte varnish over that. But after a days use in the shoes some of the varnish started to rub off. Would an acrylic sealer be better? Or is that the same thing? What about mod podge?

If anyone else has experience in dealing with painting on canvas shoes I would love some pointers. Thanks in advance for any information!