In you denomination you might not differentiate.
But the Catholic Church teaches about mortal (grave) sin and venial sin.
You knew that, didn’t you?
yes, we know that the Catholic church teaches a lot of add-ons to Scripture.
But God still doesn’t differentiate between “mortal” sins and “venial” sins.
All sin is violation of God’s command and is worthy of death.
If you break one, you are guilty of all, according to James, the RCC’s favorite author of the NT.