Subject: the difference between gazelles and impalas

k im just asking this question for my own general knowledge..not for 
school...
I was just wondering what is the exact difference between gazelles and 
impalas.  I know that they are both antelopes, belonging to the family 
Bovidae, BUT ive yet to find any reference material that would tell me 
what the difference is between them.  So far, I've only been able to 
locate material that tells me that "gazelle" is more of a common name for 
certain smaller antelopes...true gazelles belonging to the genus 
Gazella....impala's sci. name being Aepyceros melampus..which is what i 
pretty much thought.. that they r both antelopes..but impalas are not 
gazelles. BUT after doing a search on the Columbia Encyclopedia online, 
they tell me this "Gazelle is the name for a number of small delicate 
antelopes with spreading horns, inhabiting the deserts and grassy plains.  
The largest of these is the pale brown 
impala...."(www.bartleby.com/65/an/antelop.html)

so as u can see I am now quite confused and would appreciate your help 
with an answer to my question :)
thanks.

Re: the difference between gazelles and impalas