Contrary to popular belief, American English is not ebonic slang and it is very hard to definitively pin down American and British English, due to the fact that language constantly evolves. Slang does occasionally make its way into the long term lexicon, but only when spoken by a large percentage of the people. Therefore, it is very unlikely that gangsta speech or ebonics will ever be anything more than bastardized slang.
Most of the different spellings of American English (which, for all of you elitest Britons out there, are listed in the OED) developed in the U.S.'s early years, some of them created by dictionary maker Noah Webster. The differences are comparable to the ones between Brazilian Portuguese and Portuguese Portuguese.
Another interesting fact about American and Canadian English is that both dialects still use the -ize spelling for words (organize, organization, etc.), while countries outside North America have almost completely dumped it for the newer -ise spelling. However, the OED and Fowler's Modern English Usage (both of which are decent books of British origin) prefer the -ize spelling. Folks from North America also use the older aluminum spelling instead of the newer aluminium spelling. (Though neither spelling is the original; the original is alumium.)
Americans also refer to the letter Z using the 17th century name "zee" instead of the name "zed" used elsewhere (including in Canada). Rest assured, the name "izzard" is pretty much obsolete.
Sources: Wikipedia and the Concise Oxford English Dictionary.
American English: Color
American English: Neighbor
American English: realize
usually involves missing out letters, switching the order or just using the complete wrong word
closest comparison can be asking a small child to spell a word and making a dogs ears of it.
American English spellings: Color, Center, Honor, Draft