I'm looking into different armor types from the standard chainmail and plate and i keep seeing some armors that are extremely similar that i can't really find a difference. the one that gives me the most trouble is the difference between brigandines and coats of plates from what I've seen of examples they seem to be the same thing is it just the number of plates of is there some structural difference also there seem to be different styles of brigandines what benefits do these offer over the other types

Coats of plates tend to fasten at the back while brigs usually fasten at the side or front.
Brigandines tend to be better tailored than coats of plates.
Brigandines have smaller plates.

Brigandines also tend to refer to the 15th century version and coats of plates/pairs of plates to the 14th, however, a lot of eastern armourers refer to coats of plate with the term brigandine.

Then there's also the covered breastplate and Corrazinna which both get lumped together under the brigandine term in some shops. The Corrazinna has a split front and the covered breastplates have a side or back closing.

Note that front openings were primarily infantry armours due to being worse at stopping lances and the front opening only really being good for taking it on and off as a single person rather than having pages to dress you.

But basically:

Coats of plate
http://www.hoashantverk.se/hantverk/hoas_rustningar/
http://tgorod.ru/contentimage/kussnach/image3.jpg
http://cs308828.vk.me/v308828221/3acf/v1jxRLmYNVk.jpg

Brigandines
https://s-media-cache-ak0.pinimg.com/736x/b4/45/cb/b445cbf738eb0b600c7ecc9fb2444ca6.jpg
http://www.reliquary.co.uk/brig/image/make9.jpg
https://s-media-cache-ak0.pinimg.com/236x/79/f3/b4/79f3b4f8b210a87d2d8934272097220b.jpg
http://i61.servimg.com/u/f61/11/11/63/13/img_0112.jpg

Corrazinna
http://s180.photobucket.com/user/iaenmor/medi...2.jpg.html
http://s180.photobucket.com/user/iaenmor/medi...1.jpg.html
https://s-media-cache-ak0.pinimg.com/236x/2f/54/af/2f54af1aa8707c40d3292f53136feb28.jpg

Covered breastplate
https://plus.google.com/112410089144735130011/posts/6sg45yWZQiE
http://www.wassonartistry.com/images/armor/cuirasses/IMG_1446.jpg
http://lh5.ggpht.com/_aAPp22n8y_g/SuHgdra9tqI...GP5564.JPG

Another source of confusion is that many of the cheaper 'brigandines' coming out of India and a some of the more fantasy/LARP-focussed providers in Eastern Europe are actually closer to (what we would usually today call) coats of plates in their construction.

Or they're conplete tosh riveted leather, sometimes with weird squares riveted in every corner. All of it marketed Brigandine by costume shops.