Half-brother is a brother with whom one has only one parent in common.
Step brother is the son of the one’s stepmother or step mother by a union with someone other than one’s father or mother respectively.
|Definition (www.oxforddictionaries.com)||A brother with whom one has only one parent in common.||A son of one’s step-parent by a marriage other than with one’s own father or mother.|
|Synonyms||Folk, uncle, niece, mother and cousin|
|Marriage||Half-brother cannot marry his half-sister.||Step siblings can marry.|
|Related||They are biologically related.||They are not biologically related.|
|Example in Sentence||