ThisThe short answer is Yes, there is a difference.. Bolting in subframe connectors is really just the bare minimum a starting point.. The more you can do to tie the flimsy tin can together the more stable a platform it will be..
you can always bolt them in, get it running, drive it and let everything settle, then weld them in permanently later without too much hassle. You may find as @Pragmatist stated they'd be fine for what you're doing and you can always remove them later if need be. Some of us weld them, some of us bolt them. No right or wrong way, just welding them physically connects everything as one part where bolting them is a compression/friction fit which can still flex as they are not permanently attached with welds.I think I'll weld them in once the car is driving again