| ために | よう (様)に | | ---------------- | ---------------- | | volitional | involitional | | potential form ✕ | potential form ○ | | negative ✕ | negative ○ | Very often, using something +なる makes you able to use ように

上手になるように

Volition

unlike よう (様)に, it ために implies Volition: You have a choice to do it.

日本に行くために、貯金をしています For the purpose of going to japan, I will save up money.

You can choose to go to japan.

早く治るように、休んでください。 For the sake of getting better, please rest.

Getting better is not a voluntary action.

Potential form

ために can also not go with a verb in the potential form. The former is ungrammatical.

集中できる~~ために~~、(...)
集中できるように、(...)

Negative form

ために can also not go with a negative form.

「風邪を引かない~~ために~~、(...)」 「風邪を引かないように、(...)」

sources

Youtube: Yuki's TV - 【ためにVSように】WHAT IS THE DIFFERENCE BETWEEN THESE TWO!?
Youtube: Japanese Ammo with Misa - ように vs のに vs ために