Why does Guatemalan Spanish sound so different?

Spanish, like most languages, has local variations in dialect and accent. For example, in the US, there are distinctive accents in Boston and New York (and even different parts of New York).

In general, accents and dialects are most noticeable among less-educated people, because education tends to standardize language.

Mexican Spanish, although we're more used to it, sounds quite noticeably difference from Castilian Spanish, while the Spanish in Argentina and Uruguay sometimes sounds kind of Italianish to me.

My impression was that Central American countries seemed to have fairly distinctive local accents, probably because the countries were rather isolated up until recent times (for the same reasons Australians, Appalachian Americans, and some rural areas of England have strong and distinctive accents). I actually thought the accents in Guatemala were easier to understand than those in Nicaragua or rural Costa Rica.

Different from what? All Spanish, like English, has different regions, and different accents and influences that result n different expressions. For instance, in Mexico, one sees a huge influence from the Aztec and other indians of the region, that you don't see in Spanish from Spain or Argentina. In South America, there are influences from the Quechua, and other regional natives, as well as the more varied European influences, not so strong to the North. Guatemala would have a strong influence from the Mayan natives, as well as whatever European influences were strong in their region.

Not to mention the influences of the Asians who settled (mostly) on the West coasts of all of the Pacific Rim of the Hemisphere.

its kinda like how England English differs from American English every region has their own accent even if they share the same language

Depending on the region your friend is from will also depend on the dialect.. Just like Americans, people from the North East area sound really different from people in Michigan, and Wisconsin. In the South, Georgia natives sound totally different than Virginia natives. Also allot of area's also have their own language. A language known only to them, my friend speaks a language that sounds really strange to me and I'm bi-lingual in English , Spanish, and Detroit Slang(lol).

yes , i know... old the Spanish con ties speak so different... but in Cuba is really differ en and u cant understand so much really!!! the people speak SO fast

Every country has there own brand of spanish. For example Nicaraguans leave out s's a lot at the end of words, Mexicans make up a million words. Guatemala actually has a good reputation for speaking more clearly than other countries. They also tend to speak a little slower.