Democrats = Conservatives / Tories (Conservative Party is the official name, Tory is the slang from Ye Olde Worlde of Politics, when they were to the left of another group, the Whigs)

Leftists/Liberals = in theory the Labour party, but these beliefs do not properly scale USA to UK. If you mean liberal as in liberatarian, you'll find those more in the Tory ranks; if you mean Leftist as in International Socialist, there ain't many of those left in the Labour party. Generally online the terms are used interchangeably to mean "someone with economically more socialist, or socially more liberal, views than me" but don't map on to any coherent or consistent political viewpoint.