The intervening time or period.

बीच का समय

English Usage: "In the meantime, let's focus on other tasks."

Hindi Usage: "बीच के समय में, चलो अन्य कार्यों पर ध्यान दें।"

Meanwhile; during the time that something else is happening.

इसी समय

English Usage: "He is studying; meantime, his friends are playing outside."

Hindi Usage: "वह पढ़ाई कर रहा है; इसी समय, उसके दोस्त बाहर खेल रहे हैं।"