The main difference between Era and Epoch is that the Era is a an approximation of spatio-temporal bounds marked by cultural or natural phenomena and Epoch is a reference point from which time is measured
An era is a span of time defined for the purposes of chronology or historiography, as in the regnal eras in the history of a given monarchy, a calendar era used for a given calendar, or the geological eras defined for the history of Earth.
Comparable terms are epoch, age, period, saeculum, aeon (Greek aion) and Sanskrit yuga.
An epoch, for the purposes of chronology and periodization, is an instant in time chosen as the origin of a particular calendar era. The “epoch” serves as a reference point from which time is measured.
The moment of epoch is usually decided by congruity, or by following conventions understood from the epoch in question. The epoch moment or date is usually defined from a specific, clear event of change, an epoch event. In a more gradual change, a deciding moment is chosen when the epoch criterion was reached.
A time period of indeterminate length, generally more than one year.
A unit of time, smaller than eons and greater than periods.
A particular period of history, especially one considered noteworthy or remarkable.
A beginning of such a period.
A time that is used as a point of reference.
Uses in computing.
A precise instant of time that is used as a point of reference (e.g., January 1, 1970, 00:00:00 UTC).
A subdividing a period into smaller parts.
To divide (data) into segments by time period.