Apply oneself to something vs Apply to something

apply oneself to something—put all one’s energy into smth.:

• If you apply yourself to the job in hand, you’ll soon finish it.

apply to something—

1. turn to an organization for help, support, etc.:

• You must apply to the proper office for permission.

2. (of rules, laws, etc.) affect smth.; be relevant to smth.:

• These policies apply only to very large companies.