Difference between 'Home' and 'Level up' (category up) ?

I thought 'Home' give as result the section level

and 'Level up' give as result the previous category (one level up)

Ex : World (section level) > Europe (first cat level) > Germany (second cat level) > Berlin (third cat level)

'Home' ---> World (section level)

'Level up' ---> Germany (second cat level)

When we are on the 'Berlin (third cat level)' category :

When I click on 'Level up' or 'Home' I have the same result :

If I click on 'Home', the result is 'World (section level)' --> It's OK

But if I click on 'Level up', the result is also the 'World (section level)' ???

The only difference :

When we are at the Europe (first cat level), only the 'Home' icon is displayed (--> OK).

For the other catetegories, both icons ('Home' and 'Level up') are displayed (--> OK).