For the letters with one symbol, different names; Depending on whether or not it has a dot, the sound changes.
For the letters with different symbols, one name; it gets written differently when placed at the end of a word.
Qamats, Patach, Chataph Patach, and Chataph Qamats all make the "ah" sound.
Tsere makes the "ay" sound.
Segol and Chataph Segol make the "eh" sound.
Hhireq makes the "ee" sound.
Sh'va is silent.
Cholam, the only vowel placed on top of a letter, is the "oh" sound. Cholam Maley is Cholam on a vav, and is pronounced as if the vav were not there.
Qubbuts and Shuruq both make the "ooh" sound. Shuruq, like Cholam Maley, ignores the vav.