I never thought that these two words are very much alike.They differ only in one letter, but in fact they ARE quite different."Его" means "his"- possessive pronoun. For example, его собака, его дом. Он говорит о его работе.
But there are other cases of using this pronoun. We can use it instead of "him" personal pronoun used as object form of "he". Examples: He is absent- Его нет дома.He is not popular - Его не любят.
When we use "Его" with prepositions consisting of a vowel, we must use "Н" before the word. For example "У него нет денег". I hope I was of some use to you.