First Strike Coins

I'm not sure what a late strike proof designation is. The name indicates to me that the dies would show some wear and proofs would indicate it. The first strike business designation (with NGC) had to be postmarked no later than 30 days from date of release for them to grade the coin and give it the first strike designation.
They used to be issued with a red label and commanded quite the premium depending on the pop report. I haven't followed them for the last couple years, but there was a suit filed and settled about the use of the first strike designation about three years ago. I don't believe NGC uses the red label anymore and they might be a sleeper for the future. nlp

Ok for one thing the proof and business strikes are two completely different things. The proofs will have a mirrored field. The first strike designation are for business strike coins and have to be sent to the grading company within 30 days of the release date. Grading companies grade proofs and business strikes different. For example, a proof would say PR65 and a Business strike would say MS65

Proof coins and business strikes are produced with two completely different minting processes. Modern proofs will be struck at least twice with specially prepared dies. Franklin proofs are typically brilliant so they will have highly reflective surfaces. Since they are struck multiple times, the rims are squared and all details are strong- full bell lines are to be expected on Franklin proofs. Proof Franklins will typically grade high unless they have been mishandled. The primary marks will be hairlines.

Mint State business strikes will generally have overall weaker detail than proofs and the surfaces will not be brilliant. Fields will be lustrous from die flow lines and the primary marks will be bagmarks. It is very uncommon for a business strike to grade over MS65 and proof-like Franklins are exceedingly rare so it would be virtually impossible to have an MS68-69 PL Franklin.