The Macintosh 630 is a Motorola 68040-based computer introduced in 1994 1) after the introduction of the PowerPC-based Power Macintosh 6100, 7100, and 8100 families.
There were different versions of the 630 released into different markets:
Nominally, the 630 replaces several other Quadra-Centris 600-series models, although due to the Power Macintosh 6100 “already existing” and officially being those machine's replacement, whether that's strictly true sort of depends on what you think Apple was doing.
Wikipedia lists the 630 as a direct replacement for the 610. 2)
For context, Apple was making lots of weird decisions from approximately 1987 to 1997. (these dates are flexible, this is a first draft)
My thesis is that the 630 was designed as a consumer machine first and foremost. With a retail price of around $1299 (often, that was its bundled price) it cost approximately half what an unbundled Power Macintosh 6100 cost.
As The Cheap Mac at the time, replacing a group of old models and having been sold primarily as a consumer Mac, this seems clear. Part of the question here is what Apple's '90s-era badge engineering is and isn't.
General specifications for the machine 3):
As mentioned, there were several variations of the 630. Some were meant for different markets 4) and most were Performa variations meant for different retailers. The LC variation was intended for schools looking for a refreshed low cost computer, especially something with a CD-ROM drive built in (as opposed to the 475/605). The Quadra version was told into “traditional” Mac markets, alongside older Quadras (ultimately replacing them, in light of the Power Macintosh family taking the high end of that market), and Performa being a big push back into the same retail arena that the previous Performa family, where Macs weren't typically sold pre-Performa.
The 630 family is architecturally a revised 475/605, with a slightly upgraded PrimeTime II platform chip – upgraded from PrimeTime from the 475/605, itself strongly resembling the Sonora Integrated Controller from the LC III.
The 630 uses the F108 memory controller. the 475 uses MEMCjr and the 610/650/800 use the MEMC memory controller.
Apple's notes for the 475/605 suggests that they share an architecture with the 610 and 650. That's sort of true. 475 uses MEMCjr, a cut down version of MEMC, but 630 revises that further to F108, which is likely just a revised MEMCjr.
From the 475 to the 630, a lot of functionality moves out of the platform controller into the memory controller, in part due to adding IDE. The other major change is that graphics moves out of the memory controller and onto its own entity on the 040's processor bus, for the 630, to enable integrating analog video and probably affording the 630 its graphics speed boost over the 475. Valkryie is said to offer some acceleration that certain games use, as well.
The platform chip in the 610+ is IOSB, which will be appropriately beefed up to handle the Kiwi NuBus controller.