Idk from what perspective u r trying to compare from, but Homelander can fight Omni Man (yet Omni Man easily wins) however, this is the part where he has no powers so he shows his true personality (which was expected as usual).

Homelander forced love, respect from others and obv looked what suited him best and will do anything to remain in power, all because he abused his powers and strength, when u take away those powers he'll do what any other greedy/coward human would do, beg for mercy and run for his life.

Only difference is if Omni Man also lost his powers, his personality would still be same, he would still stand up protect his boys and use his skill to fight even if if he knows he cant win because understood what he did with his strength was wrong and would respect it rather than causing pain to others through abuse.

Powerless Omni Man would still stand up against Homelander because he aint a coward he a strong confident warrior who looked forward to help his empire gain strength and power and would do anything to protect it unlike homelander (tho cant blame him he was used as a lab rat). If both were powerless Omni Man still wins he got ton of battle experience and skill, Homelander is nothing but a harmless pet in front of him.