Lean means incline or tilt; lien is a legal claim.
e.g. Stand up straight and don't lean against the wall.
e.g. There is a lien against your house if you don't pay its property tax.
Recourse / Resort
Recourse means an appeal to; resort means turn to for help.
e.g. We may have recourse to compulsion.
e.g. If there is no solution, we may have to resort to force.(as a verb)
e.g. We may have to open it with a knife as a last resort (as a noun).
Indoor / Indoors
Indoor is an adjective; indoors is an adverb.
e.g. Basketball is often an indoor game.
e.g. It is raining; we'd better go indoors.
Smother / Smolder
Smother means cause difficulty in breathing; smolder means burn slowly.
e.g. For a while, we were smothered by the dense smoke.
e.g. The ashes at the fireplace were still smoldering.
e.g. For years, hatred smoldered in her heart.
Regardful means paying attention or showing respect for; regarding means concerning or relating to.
e.g She is regardful of all her customers.
e.g. Regarding this matter, I think you didn't get it right.
Infamous / Notorious
Infamous means evil or wicked; notorious means well known for something discreditable.
e.g. He was an infamous kidnapper.
e.g. Everybody knows that she is a notorious liar.
Read my most recent publication: Everyday American Idioms.for ESL Learners.(to get the paperback edition, click here)