what is the difference?

There a several 7mm cartridges. If you mean the 7mm Remington Magnum (or just "magnum") The magnum is about 300fps faster than the 7mm-08. This means flatter trajectory and more recoil.

If deer is on the menu go 7mm-08 its plent of punch for a deer, is still considered a "flat" shooter, isn't rough on recoil and is accurate.

7 mm is the dia. of the bullet being 0.284” ø and 7 mm-08 is the cartridge ( brass ) that holds the 7 mm bullet...

so when somebody says that they shoot a 7mm-08, they are basically saying they shoot a 7mm? (not referring to 7mm mag, just 7mm and 7mm-08)

No, it means that they are shooting the 7mm-08 cartridge, usually people don't refer to calibers as much as cartridges, they're both two different things.

Caliber, is the diameter of the bullet, but cartridge can have a number of variations.

For example, the 30-30 Winchester, the 30-06 Springfield, and the .300 Winchester Magnum are all .30 caliber, but the cartridges are different, like the casing is different, the length of the bullet can be different.

So, generally, people are talking about the cartridge, not the caliber, I say "I shoot a 7mm-08.", not "I shoot the 7mm caliber.", because people will wonder which 7mm the guy is talking about.

The diff? Well... what cartridge? 7mm Mauser, 7mm Mag, 7mm-08, 7mm STW, etc... ?

Common are 7mm-08 and 7mm Remington Mag. Diff? For the most part... 7mm Mag hits harder further (at ranges most shouldn't be shooting) and is louder, recoils a LOT harder, ammo much more expensive... and it scratches that Magnumitis Itch. Some can make good use of its extra power, most (deer hunters) have no need of it.

Yes, it could get very confusing if you don’t include the cartridge size...

thanx for the help, im fairly new to the gun scene and i dont always understand when somebody is talking about cilber orcartridge so this has helped immensly and numerous other items are a lot clearer now. thank you all for you help.

Just a little something to look at on what we were talking about if you’re interested...
www.chuckhawks.com/rifle_bullet_diameter.htm

thanx