Indiscriminate and indiscriminating both mean “lacking distinctions,” “haphazard,” “careless or confused,” as in Her indiscriminate buying of clothes made her dress oddly indeed and Her tastes were indiscriminating. But indiscriminating is used much less often than undiscriminating, which means “making no choices, without making any distinctions,” as in Her choice of music seemed bafflingly undiscriminating. Undiscriminating (the synonym undiscriminate is rare in American English) can be pejorative, but indiscriminate almost always is.
