Specifically in Christian contexts, referring to the fallen angel.
キリスト教では、ルシファーは堕天使とされている。
In Christianity, Lucifer is considered a fallen angel.
Lucifer; Venus; the Morning Star
Astronomical/poetic name for the planet Venus as the morning star.
明けの明星はルシファーとも呼ばれる。
The morning star is also called Lucifer.
Extended use: a devilish or demonic figure, not necessarily the biblical Lucifer.
彼はまるでルシファーのような悪魔的な魅力を持っている。
He has a devilish charm, almost like Lucifer.
明けの明星 is the plain Japanese term for the morning star (Venus), while ルシファー is a more poetic, Latin-derived name for the same phenomenon.
天使 means angel, the heavenly counterpart to ルシファー, who is the fallen angel turned devil.
堕天使 is the general term for any fallen angel, while ルシファー is the specific named figure most famously identified as one.
From English 'Lucifer', ultimately from Latin 'lucifer' meaning 'light-bringer'.