The marriage system of ancient times differs from that of the modern era.
Tips
register
Slightly literary / formal. The pattern 与 X 有别 ('differs from X') is especially common in academic and analytical writing. In casual speech, you'd more often hear 不一样 (different) or 不同 (different).
grammar
有 (have) + 别 (distinction) = literally 'have distinction'. The same 别 root gives 区别 (distinction), 差别 (difference), 分别 (separately / to distinguish).
