BAR: stands for Browning Automatic Rifle. John Browning invented the rifle during the end of WW1. It was used in WW1 and WW2. It shoots the famous 30-06. It's a fully automatic rifle with a 20 round magazine.
M14: The M14 replaced the M1 Garand. It shoots a 7.62 NATO. It has a similar design to the M1 Garand but instead of the clip it comes with a 20 round magazine. It had a pretty short military life. It was a heavy gun and was really hard to shoot full auto. It was eventually replaced with the M16.