Then WHAT(?) constitutes a “Horse-Collar” tackle?

During Teddy’s first drive, right after the Latimore’s Int., we had made our first , first down, so, 1st and 10 with a hand-off to Washington from The J-E-T-S’s 19, the defender who is given credit for the tackle but is clearly shown with his hand inside of Wash’s pads but at the chest level from the front! My ? is; is the definition of a horse=collar tackle ANY grab inside of the shoulder pads or what? Then , if so? Why not call it on that play where it’s rarely MORE OBVIOUS as the way Hewitt, #46 for the jets, is seen bring Alvin down ( along with a number of other jets on top of the pile) but clearly Hewitt brought AK #41 down by the FRONT of his shoulder-pads but nonetheless, to me, this is unabashedly a tackle which gives those rinky-dink defenders an obvious and clear way to make a tackle a tackle proof All Star Player in Alvin Kamara and I’m asking if ANYONE has ever seen this call when it’s a clear grab of the pads to bring down a player from the front? Please give us a bit of insight, if you have any, concerning such a clear infraction of the rules or am I not reading the rule correctly and it only applies from behind the player? Merci Mes Amis and GEAUX SAINTS GEAUX!