]1. I think both are meant for 1 time use.
2. The sealant is the same.
3. Rings are reusable, for ever if not rusted or otherwise damaged.
4. Lids are FAR cheaper to produce/manufacture than the threaded complete 1 piece that the packagers use.
5. For the mass packaging industrial process, the 1 piece is cheaper due to the automated filling/sealing machinery.
The bottom line in canning is, sealed is sealed. What difference does it make if it seals?

That is true, but the seals are designed and intended for 1 time use. They do not work very well when re-used. Compare a new one to a used one.
Sort of like gaskets in an auto. I'd never replace a cylinder head and use the same gasket.
Might get lucky, but I wouldn't expect it to last very long.
Meats and low acid stuff needs strict attention to details for good results. [/quote]

Depends on the lid.
What was canned and if it was water bath or pressure canned.
Kettle canning has very little effect on the seal.
Pressure canning does have more effect on the lid, but the old lids before 2000 have thicker rubber seals and thicker metal.
I reuse them, just mark the lids as to what was canned with them.
I don't mix pickled lids with corn, or fruit.
Tomatoes will stain the lids , ( remember I'm using lids pre 2000, that still have the white Ceramic coating, and wider and thicker rubber seals.