The brand of the overalls in the picture is True Face, cheap on Amazon UK

The dude on the right is wearing Osh Kosh B'Gosh overalls. What about the guy on the left?

The answer to your question is old navy. The guy on left is wearing old navy overalls. Old navy no longer make overalls though.

They still do ;-) But not for Boys ...

https://www.oldnavy.com/products/denim-overalls.jsp

I like the yellow t-shirt in combination with the old navy overalls.

I really like the look of his bibs!

For the record the era of these Osh Kosh B’Kosh Bib Ovies our cute little ham is wearing are from at least the “Early 80’s”. I know I had a pair. Mine were for “larger and or older tweens”. Loved ‘me! His Mom managed to run across a great find at a garage sale or second hand store! A little ironic that they’re from my long gone childhood given our cute little one’s age! His Mom or Dad’s got great taste in “Vintage Ovies” for their boy. Kudos to you Mom and Dad!!