What do these command do?

sudo apt-get install linux-image-generic-lts-backport-natty 

                     linux-headers-generic-lts-backport-natty

Does it install just a new Linux version or something more?

And what about:

sudo apt-get purge linux-image-generic-lts-backport-natty 

                   linux-headers-generic-lts-backport-natty

Does it just remove the packages installed by the previous command? (or does it more?)

If I am correct in all cases why it doesn't work? I get an error, so it means it's not true and something else had happened?

Edit:

as it was said that second command doesn't remove it, then would this command remove it? aptitude autoremove