Hi, I live in the US and we often say 1st shift when we mean the morning shift, 2nd shift would be starting in the afternoon, and 3rd shift starts very late and goes until morning. This varies greatly depending where you work and live and also assumes you are talking about 8 hour shifts. If someone told me they were working the early shift, I would assume morning and if they said late shift I would assume 10 or 11pm until early morning. I hope that helps you decide if they are synonyms or not for your situation : )

what is your skype id

The terms could have the same meaning. These types of phrases often vary, relating to policies of the particular organizations.

No. You should be able to figure this out for yourself.