high-growth era; period of rapid economic growth
Refers specifically to Japan's post-war period of rapid economic expansion, roughly from the mid-1950s to the early 1970s.
During the high-growth era, many Japanese companies grew rapidly.
With the end of the high-growth era, the economic structure changed.
高度経済成長 refers to the rapid economic growth itself, while 高度成長時代 refers to the era or period characterized by that growth.
Compound of 高度 (high degree) + 成長 (growth) + 時代 (era). The term is historically associated with Japan's post-war economic miracle.