I had a SS on the Beyond in March and the Edge in August (post-cuts). These were my observations:
In March, our Butler was ever present. We asked her for very little but she was always around and asked us about our needs and made suggestions. Like coffee every morning and when she saw I liked a certain pastry, a basketful came every morning. She would stay a few minutes and chat, and tell us about the day (tender info, timing, or whatever). She saw we had laundry and took it away and brought it back a day later (an Elite perk, not a suite perk). She met us at the theatre on chic nights with reserved seats and our drink order ready. We saw her around the ship especially in the suite lounge, and she always asked if we needed anything. She offered to pack and unpack (declined politely!) and even on departure morning she saw us in the hallways and insisted she help our luggage off (declined, again!). She was in our suite every day (maybe multiple times!) arranging the temperature, closing the shades if it was too hot, brining waters, sodas, ice, etc. She chilled our champagne as requested and left little treats without asking. She noticed any maintenance issues and resolved them before we could even ask. Our stateroom attendant was not visible, but he did an excellent job at keeping our suite clean 2x daily. So, our butler was front of house, and our attendant was back of house. Both excellent.
Contrast to the Edge in August. Our attendant introduced himself as "Retreat Team" which was on his name tag. He said he just got a new title and to ask him for anything we needed. In the end, the "retreat team" is a cabin attendant with a new title - and he wasnt only dedicated to suites but had a line of regular cabins to attend to. The head butler came and introduced herself and said she is the boss of the retreat team and to call her if you are not getting what you need. But it was clear we did not have a butler. While our attendant did a good job, he was clearly exhausted. No special treats, no fruit baskets, etc and he made it clear the mini bar, including soft drinks, was not included. Our champage was never chilled and he never offered (to be fair, we forgot about it and never asked). We had maintenance issues and we had to call him as well. He took our laundry back and forth. Again, he got the job done, but it wasnt anything more than in a regular cabin. There was no offer to bring coffee or anything else. We did use room service for AM coffee and it was delivered on time by a member of the room service team, not the retreat team. The retreat lounge seemed overwhelmed, and there were three retreat hosts and they also seemed very busy. On the Beyond, the butlers served afternoon tea in the lounge and checked on you to be sure everything was OK, on the Edge it was self serve. The reserved seats for Chic night was more administrative than personal. Show your suite card and get in. Again, it was fine but not personal.
So, saying all that (sorry, long winded!), the main difference is in the level of personalization and connection. We essentially got every perk on the Edge that we did on the Beyond, but it was without making connection and sometimes having to do it ourselves, like ordering room service or stocking our fridge with takeaway soft drinks from the lounge, etc. That was fine for us and it did the trick.
BUT, the two takeaways for me are that Celebrity changed this without telling us and after we booked and paid. Not fair. And, it seems like the bubble is going to burst soon -- they all seemed overworked and overwhelmed.
As long as there are no more changes, I would book at SS again. If they remove Luminae, Retreat deck, etc from SS then I'm gone!