Answer
Both are summary ejectment actions under Rule 70 to recover physical possession, but they differ in how the possession became unlawful. In forcible entry, the defendant's possession is unlawful from the very start — he takes the property through force, intimidation, threat, strategy, or stealth, and the plaintiff had prior physical possession. In unlawful detainer, the defendant's possession was originally lawful — by contract or by mere tolerance — but became unlawful when it expired or was terminated and he refused to leave despite a demand to vacate.
Both must be filed within one year in the first-level court, and both settle only possession de facto; any ruling on ownership is provisional and made solely to resolve who is entitled to possess. If more than one year has passed, the remedy is no longer ejectment but an accion publiciana or an accion reivindicatoria.