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Only a 555 can replace a 555, there is no equivalent. 555s are made by many companies, each with their own prefixes and suffixes, but all are 555s.
555 an IC which can be used for many applications and one of the application is astable multivibrator. For many applications we use IC 555 because its cost effective and have lot of features.The main difference is astable multivibrator switches from one state to another state automatically i.e when a pulse is given to astable multivibrator, it immediately switches to high state and remains for certain time and switches back to low state. In 555timer you can decide your own application.