Hi amyele ,
If you are talking about the previews, they aren't really a quality criteria to judge your pictures. Generally speaking, the considerations of Shutterstock and Adobe Stock are similar. It may be that a picture being accepted by one gets refused by the other and vice versa, but 99% of your images that passed Shutterstock should pass also here.
Shutterstock is not as focused on Reasons content is rejected at Adobe Stock / Commercial appeal. I have pictures accepted there, that got refused here (and for good reason I have to say...).
But most of the decisions are consent and acceptable on both sites. But as humans are doing the checking, sometimes there are difficult to understand decisions just because the moderator took the wrong refusal decision. I do not know how much time they have for the decision, but I suppose, it‘s not a lot per image.
But they have quite a suborn customer care service, where you can prove your case and still hit granite.