Correction in the title: ما الفرق بين
أسكن = I reside
أعيش = I live
وصل = He arrived
أتى = He came
لسبب is more general. It means “for a reason”.
بسبب is specific. It’s used to give a reason, i.e. “because of”.
كل شيء يحدث لسبب ما = Everything happens for a reason.
فرضت الحكومة حظر تجول بسبب الوباء = The government imposed a curfew because of the pandemic.
صادف = he chanced upon
لقي = he found