I'm guessing you are referring to the size and run support in saying they're similar, because Sherm has always required safety support over the top in coverage and he's always had it. Which is one of the reasons why some other renowned corners check him when he shoots his mouth off too much. He never had the talent, the raw speed and twitch that you need to be an elite corner and the DBs know that.
Ramsey is just a whole different animal. He's got the raw talent, the twitch and speed, the instincts etc you need to be elite on top of that size and aggressiveness and ability to play the run. Personally I'm not a fan of the guy though, I think he has a lot of growing up to do and that might not come until after his career is over. But there is no doubt that if he's bought-in mentally that he's gonna deliver.
Last year was quite bad for him too btw. And this is effectively a contract year. So we're about to see his best and be reminded what this dude is capable of.