in general, does one look for in frame construction, beyond the material(s)? i've seen a lot of comments that mention stuff such as "butted, double butted", etc.
I publish MY "TEN SPEEDS" just for people like the OP, new to the vintage bicycle interest and seeking a fast track to learning. With the OP's question in mind, I offer
Vintage Bicycle Quality, an article focusing on what to look for when trying to determine a bicycle's quality level.
Hope it is a help.