No, it's not about Marriott vs. SPG. The service you receive, including whether a separate check in line is open or you get a "briefing" is dependent on each individual property. My last stay was at a Westin. Did mobile check in, no separate line. No briefing. No "thank you for being Titanium" (which I don't care about but noticed since it almost always happens). Then I asked if they had a package for me which had arrived the day before. She called someone on a walkie talkie and he said he was going to lunch and he'd look later.

Overall, not a bad experience, certainly not one that prompted a complaint, but not ideal either.