"Standard" jobber-length drill bits uaually have a 118 degree included angle between the flutes. They're good for drilling plain steel and some alloys that are harder than normal. The 135 degree bits have a little more aggressive cut in softer metals such as aluminum or brass, and don't do well with tough alloys. As the angle gets flatter and the speed is slowed down, harder metals can be drilled more efficiently.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!