DVD issue

[bluedestiny]

Ok ya, I really want to purchase some dvd, but i keep getting confuse by these name for example
What are those MAC, M, and that little circle after the title of the dvd, are there any other?
http://www.import-anime.com/index.php?pa...n=dosearch
http://www.import-anime.com/index.php?pa...n=dosearch
http://www.import-anime.com/index.php?pa...n=dosearch
http://www.import-anime.com/index.php?pa...n=dosearch
What the different between perfect colleciton, tv series, and ova (i don't need to know the acrynom, just what is the difference)
thank you guy, not sure if this is in the right forum, this is my first time here
hope i make some wise choice to order these anime