TheValkyries
proudly reppin' 2 superbowl wins since DEFLATEGATE
If the RB runs a draw play and his offensive line (which has 5 fat guys in the way of the 4) doesn't block... then yes, the 4-3 is stronger against the run.
If they actually block and the front four lose contain, there's only three linebackers to safeguard a quick gash. A quick run to the outside gets 8+ yards easy on a 4-3. Whereas against a 3-4 it only gets 4-5 max. Meanwhile, a miscue on a linebacker gets another easy 8+ yards with a draw play despite the fat guys in the way, if the offense blocks well.
A 4-3 is generally strong on the draw, and immensely vulnerable to an outside run. The 3-4 is strong against both, because there are more backers who can step up and stop a run at two yards, and minimize the effects of an outside run. Thus, the 4-3 is weaker to the run than a 3-4. It puts all the eggs in one basket so to speak. There's also a lot less freedom for the linebackers as well, because one screw up means a big play. Whereas in a 3-4 there's a bunch of checks on a run play just inherently in the formation.
The reason a team goes to the 4-3 is to Pass Rush, which is something that is hard for the 3-4 unless they have either a stud Defensive End (Read Cowboys or Texans), or they run a Hybrid Defense that blitzes often, and sometimes throw a down linebacker at them (Read Green Bay Packers). The Pats didn't have the personnel to run either, so the 4-3 was only a logical decision. Belicheck prefers the Hybrid 3-4 considering he was the Defensive Coordinator that popularized it, if not invented it.
EDIT: This should all be in discussion... POST PICKS IF YOU GOT EM.
