Lifelong vs Longtime - What's the difference?

As adjectives the difference between lifelong and longtime

is that lifelong is extending for the entire duration of life while longtime is having endured for a long period of time.

* life-long, life long

(-)

Extending for the entire duration of life.

They were lifelong friends; they met in elementary school and ended their lives in the same rest home.

* long-time

(head)

Having endured for a long period of time.

My longtime friend, since birth actually, called and gently broke the bad news to me.

* long-standing * long-term

* new * short-term

* long-timer