Nope, they're the same thing just like Kamui and Kaguya's S/t. All Mangekyo feats are smaller scale versions of her RinneSharingan jutsu.
No. Kaguya's space time jutsus are amenominaka and yomotsu hirasaka. They grant Kaguya access to 6 different dimensions with various properties, and of course the portals can also be used for travel. These techniques are most definitely completely different jutsus than kamui. Even Kaguya's portals are shaped more like blocky rectangles while kamui is more like a spiral in space time. Kaguya can also alter the properties of her dimensions (where as Obito hasn't been shown to be able to do that with Kamui's dimension). Obito also has access to only the one dimension.
As for tsukuyomi and infinite tsukuyomi, normal tsukuyomi doesn't have the connection to the shinju that the infinite tsukuyomi does. Normal tsukuyomi doesn't turn people into white zetsus.
Do you see what I'm saying? Just because two techniques are similar in some aspects does not mean that they are the same thing.
What's more, where is your proof to back up your theory? I do not recall a manga panel or a guide book saying that mangekyou techniques are scaled down rinnesharingan techniques.
If your theory is to be believed, then where is the rinnesharingan's equivalent to amaterasu or Shin's telekinesis?