No they aren't. I don't need a number line to show you. 3/4 is .75 while 3/8 is .375 if you wanted a fraction that was equivalent but still used 8 as the denominator then you would go with the fraction 6/8. Also a thing to note since the denominator of
6/8 is twice that of 3/4 we know that the numerator must be doubled too. I hope that helps.