Mid term Election---When elections are held much before the schedule, it is considered as the "Mid-term Election". The President can dissolve Lok Sabha and call a general election before five years is up, if the government can no longer command the confidence of the Lok Sabha, and if there is no alternative government available to take over.
Bye-election-- A special election to fill a vacant elective position with an unexpired term due to demise or resignation of the occupant.