The difference between Become and Shape up

When used as verbs, become means to arrive, come (to a place), whereas shape up means to improve.

check bellow for the other definitions of Become and Shape up

Become as a verb (intransitive, obsolete):

To arrive, come (to a place).
Become as a verb (copulative):

To come about; happen; come into being; arise.

Examples:

"What became of him after he was let go?"

"It hath becomen so that many a man had to sterve."
Become as a verb (copulative):

begin to be; turn into.

Examples:

"synonyms: get turn go"

"She became a doctor when she was 25."

"The weather will become cold after the sun goes down."
Become as a verb (transitive):

To be proper for; to beseem.
Become as a verb (transitive):

Of an adornment, piece of clothing etc.: to look attractive on (someone).

Examples:

"That dress really becomes you."

Shape up as a verb (intransitive, idiomatic):

To improve; to correct one's bad habits or behavior.

Examples:

"He'd better shape up soon, or he'll fail the class."
Shape up as a verb (intransitive, idiomatic):

To take shape; to transform into or become.

Examples:

"The fog has vanished and it's shaping up to be a beautiful day."