Question

Difference between coin are tossed simultaneously vs coin are tossed one after another

Answer 1

Coins are tossed simultaneously means coins are tossed at the same time, that is both coins are tossed together while coins are tossed one after another means that first one coin is tossed and after tossing of first coin the other is tossed.
Hope this helps :)

Answer 2

Coin tossed simultaneously means that two or more than two coins are tossed at once.
However coin tossed one after the other means that the sample space I.e the total number of possible outcomes is taken of only a single coin at once for individual observation and not for multiobservations for many coins tossed at once.