Yes, Marmite and Vegemite are the same product.

And yes, they both taste like the floor of a pub after a team of Guinness-drinking rugby players have had a party.

And as for spreading thinly? I shared an office with an ex-pat Brit who loved his Marmite and I tried a teeeeeeeny, TEEEEEEENY bit on the tip of my baby finger. I couldn't wash my mouth out fast enough. And this was in a university science building that had sinks in their offices.....

Of course, Europeans think North Americans are nuts for loving peanut butter, so to each their own.