Birth chart

when calculating birth chart without birth time can be considered accurate? I tried with my birth time and without, the result was different. When I put my birth time, my ascendant was pisces, while without, it was virgo.

To get a general gist of a person you can sorta do without the exact time. But as you said you did notice these differences.

Depending on the day your moon can shift which in my case if I was born in the day time it would place my Moon in Aquarius. If I can recall the Rising changes every 2 hours, roughly 24 hours each day as it cycles through all the signs.

Rising can make a difference depending on its influence, it's your mask you wear to deal with acquaintances and strangers alike so getting it wrong may throw out your whole perception of the accuracy of astrology.