Given the limited information in your question I can only give a general reply. The caliber is the diameter of the rifle groove to groove in thousands of inches. So the difference would be .450" - .308" which equals .142". There are a lot of specified rounds of ammunition that use .308 and .450 bullets. In general the larger caliber bullet would also be more powerful.
A lever action rifle chambered in .308 Winchester.
No You could build a rifle in .306" or any other caliber but you are likely referring to 30.06. A 30.06 rifle is referred to as "30 Caliber" but to be accurate it is nominally .308"
About 3,400 yards.
900 meters, depending on the rifle, sights, and skill of the user.
Neck angles, headspacing, pressure generated by the cartridge when fired.
The numbers .308 are the caliber of your rifle,not the model number.Please include the model number and serial number to get the age of your Winchester rifle.
100-1000 usd
You will have to me more specific. Do you mean any rifle that fires a 30 caliber projectile or 30/06 or 308?
The .50 caliber is larger in diameter than the .308. If you are referring to the bullets for the .50 BMG and the .308 Winchester, the .50 is MUCH heavier, and much longer than the .308.
The actual diameter of the bullets are both 30 cal. The brass casings are different for each rifle. Therefore, to distinguish between the two, (since they are both 30 cal, you can't call them both 30 caliber, or else you'd get the bullets mixed up for each rifle) they label the 303 by the diameter between the "lands" (.303 inch from the rifling surfaces in the barrel) the 308 is measured from the grooves. (.308 inch from the depth of the grooves instead of the surface of the lands.) They both fire a 30 caliber bullet, but they are designated using different measurements in order to keep from getting the different size casting mixed up between rifles.
No such rifle. The Lee Enfield was made in caliber .303 British, not .308. The closest thing would be the Ishapore 2A or 2A1 rifle, made in caliber 7.62 NATO. While similar the .308 Winchester, it is not the same, and .308 should not be fired in a 7.62 NATO rifle. The Lee Enfield "sniper" rifle in .303, if original and complete (and not an aftermarket conversion) may sell for around $1500, depending on condition and accesories. There are many fakes on the market- be sure of what you are buying.
4x, 1-4x, 3x9 are all candidates