I could have little details wrong, but Universal/Topstitch/Ballpoint describe the characteristics of the needle. The ballpoint needle has a rounded point so that when it goes through knits, it will slide past the fibers and not pierce them, which can cause running of knit fabrics. Universal needles are a cross between a ballpoint and a sharp needle. The tip is sharper than the ballpoint, but not as sharp as the sharp, so that it does well on almost all types of fabric but isn't the perfect needle for any one fabric. Topstitch needles are sharp needles with larger holes for the thread and deeper scarves (the groove along the needle where the thread sits so it can slide through the fabric without so much friction). They were, I believe, originally designed for topstitching fabrics like jeans. All needles can come in different sizes, so there will be topstitch 70s, 80s, ... and ballpoint 70s, 80s, etc. Thread hole sizes and the diameter of the shaft and things like that will change with different needles sizes. But that change is relative to the other needles in the same class. So, for example, topstitch needles are designed for heavier threads so a topstitch 90 needle will have a larger thread hole than a universal 90 needle or a topstitch 80 needle.
(Sorry if I got any of the small details wrong.)