Which of these are the best for sun protection--covered up or cream?

Both: Cover-up with a proper materiel can block uv exposure completely and it lasts as long as you wear the cover-up. The same can't be said about creams which can be washed, sweated or wiped off. However, unless you can go out in public in a burqa, you need some sunblocks for the face and hands and sometimes cover ups just aren't practical. Use both for the best of both worlds!

Depends: Some t-shirts are made to block uva and uvb radiation. These are usually marketed to boaters, fisherman, etc. Normal clothing blocks most uvb but not uva . Sunblocks can block both or only uvb as well. You need to read the specific coverage of the sunblock.