12:00 Noon, 2 days earlier.
Strictly speaking, there is no 1200 PM. There's 12 noon and 12 midnight. 12 noon is 1200 hours.
Noon
Three hours.
3:00 am
There is no such time as 12 pm. There is either 12 noon (= 1200 hours) or 12 midnight (= 0000 hours).
Noon would be 1200 hours or 12:00.
12 Noon
1200 is Military jargon for Noon and 2400 hours is actually 12:00 am (midnight)
a.m is an abbreviation and means before noon ie before 1200 hours. It comes from the Latin words ante meridiem (translated into English it means before midday) p.m is an abbreviation and means after noon ie after 1200 hours. It comes from the Latin words post meridiem (translated into English it means after midday)
1200 NOON
There is no such time as 1200 am: there is 12 noon and 12 midnight. The question cannot, therefore, be answered.
Neither. 1200 am is noon, and marks the division between morning and afternoon. 12:01 is afternoon. 11:59 is before noon, or morning.