Como dizer "Letra Maiúscula/Minúscula" em inglês

Hello Guys,

Just to make sure, to say "Letra Maiúscula/Minúscula" in English is Capital letter and Small Letter?

for example, to spell AbCdEf, should I say: Capital letter A, small letter b, Capital letter C, small letter d, and so forth... is it right?

I've seen something as lower case as well, so could someone help me out? I need to get to know this kind of thing to use on the phone.

Thank you so much!