Differences in the capitalization of my name

This should not cause any problems. People working on graduate admissions typically quite well understand that different systems mess with names in different ways. Certain types of permutation might cause difficulty, but ALL CAPITALS versus Standard Capitalization is so routine as to likely go entirely unnoticed.

There is absolutely no issue here. Although we traditionally use capital letters for only the initial letters of names^* and school teachers will tell you it's wrong to do otherwise, the capitalization isn't considered to be part of the spelling. Rather, it's part of the orthography of the langauge, which is the set of conventions we use when writing it down. Thus, "Sabbir Hasan", "SABBIR HASAN" and "SaBbIr HaSaN" are all considered to be the same name. The choice of capitalization is more similar to the choice of a font than a choice of spelling.

^* This is a simplification, as Ronald MacDonald, Ludwig van Beethoven and e e cummings will explain.