Thread:Sakurairo/@comment-30379300-20170821235824/@comment-29752621-20170902202928

They're basically the same but:

Each time a set of PR and SR is available or a new promo gacha, using blue stars allows you to draw one 1-draw for 6 stars and one 11-draw for 160 stars (the "SALE" you see all the time in the gacha box)

Rarely, they have blue-star only sales which can give you a guaranteed PR for an 11 draw (250 blues) (only happened twice)

You lose all of your current blue stars if you transfer between OS (android <-> ios) (best to just use them all before you transfer if you can help it)