What is Difference between `msg.chat.id` and `msg.from.id` in Telegeram Bot?

What is Difference between fromId and msg.from.id in Telegeram Bot? Apparently, both are the same and Return user id.

bot.sendMessage(msg.chat.id, 'Hi', opts)

and

bot.sendMessage(msg.from.id, 'Hi', opts)

via Sedric Heidarizarei