Biggest difference to my view is the M-16 is easier to train newbies. Additionally, it is simple to trouble-shoot and maintain.
M-14 came and went away. Entire warehouses of M-14 rifle were destroyed during Clinton Administration. Now it appears to be back as a tactical weapon for certain occupational specilities within USA Armed Services.
I'm certain the M-16 holds the record for longest life as a standard issue rifle. Many upgrades since the Viet Nam era has brought a better weapon into the hands of American troops.
I'm also certain that Lobbyists seek to bribe those in Washington to scrap the M-16 in favor of a new rifle. Since our nation is well over $700 billion in debt, I think its just plain foolish to seek to replace the M-16 at this point in time.
Fire up the grill! Deer hunting IS NOT catch and release.