Hello Mehrdad! These two words mean different things. "Blousy" is an adjective describing a woman with large breasts due to the prominence of her full blouse. "Blowsy" is an adjective describing a woman as being coarse (rough and unrefined), untidy, and red-faced - little rough around the edges. I hope that helps!

Yes, blowsy is by far the most common spelling, but I wouldn't be surprised if you encountered "blousy" or even "blowzy".