What is the meaning of "Then Allah caused him to die for one hundred years and then raised him up" in Surat Al-Baqarah, and what is the difference between an 'ām (عام) and a sanah (سنة)?

The meaning of the verse is that Allah Almighty caused Uzair to die for one hundred years, then brought him back to life and resurrected him. He caused him to die in the forenoon and brought him back to life in the late afternoon before sunset.