Red dot is a large flake powder. Bullseye a relatively small flake. I have found that both meter fine in my ( mostly lee disk) powder measures.
IMHO, red dot is a good versatile powder. Certainly worth keeping around. That said, I've loaded it in 380 acp, 38 spl, 9mm, 40 and 45 acp ( as well as 12 ga shotgun). I've just never found any application where it was the best powder for a particular application.
Enjoy your new opportunity to experiment!
P.s. Google "Pistol Powder Comparison Pictures" and you'll find an interesting thread on the topic on another forum. It is complete with macro pictures of several powders including the two mentioned here.

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Dave