1.
If you dress up or dress yourself up, you put on different clothes, in order to make yourself look smarter than usual or to disguise yourself.
You do not need to dress up for dinner...
Little girls dress up as angels for fiestas.
PHRASAL VERB: V P, V P in/as n
2.
If you dress someone up, you give them special clothes to wear, in order to make them look smarter or to disguise them.
Mother loved to dress me up.
PHRASAL VERB: V n P
3.
If you dress something up, you try to make it seem more attractive, acceptable, or interesting than it really is.
Politicians dress up their ruthless ambition as a pursuit of the public good...
However you dress it up, a bank only exists to lend money.
PHRASAL VERB: V P n (not pron), V n P
4.