They both puffed out their cheeks when playing. Dizzy's were more predominant that Satch's, however.
I’ve seen many pictures of Louis Armstrong playing the trumpet and do not recall any showing poor tecnique.
Thank you. IIRC, it was the jazz style to do that, unlike the classical world which of course was very staid and proper. It was the DIXIELAND jazz style, which was all about the New Orleans joie de vivre, unlike “cool” jazz which came along later. It’s all good.