They're both swearing.
The 2nd is more coarse in my mind, so a liitle more intense in swearing. This is probably subjective.
I have to say, the expressions you've mentioned are rare to non-existent where I am - sounds very American to my ears.
'This sucks' is a different matter. Common where I am and milder in tone. Yes, you can add whatever you want at the end to make the expression as polite/vulgar/coarse/ as you want.
'This sucks', or 'This sucks big time' are fairly neutral in that no one will be that shocked to hear it.
'This sucks like hell' is similar. The 'hell' gives it a bit more emphasis.
'This sucks shit' is coarse and swearing, as are your examples earlier.