In modern American politics: nothing. Both words have been entirely detached from their original meaning by the conservative element and perverted into buzzwords that mean nothing semantically accurate at all. Now these words simply mean "the evil enemy," which is inaccurate in every important way.
Socialism is more of the far left extreme. Liberals are still kind of capitalists mixed with some socialist ideals.
open to new behavior or opinions and willing to discard traditional values.
"they have more liberal views toward marriage and divorce than some people"
favorable to or respectful of individual rights and freedoms.
"liberal citizenship laws"
synonyms: tolerant, unprejudiced, unbigoted, broad-minded, open-minded, enlightened; More
permissive, free, free and easy, easygoing, libertarian, indulgent, lenient
"the values of a liberal society"
antonyms: narrow-minded, bigoted
(in a political context) favoring maximum individual liberty in political and social reform.
"a liberal democratic state"
synonyms: progressive, advanced, modern, forward-looking, forward-thinking, progressivist, enlightened, reformist, radical More
"a liberal social agenda"
antonyms: reactionary, conservative
of or characteristic of Liberals or a Liberal Party.
(in the UK) of or relating to the Liberal Democrat Party.
"the Liberal leader"
regarding many traditional beliefs as dispensable, invalidated by modern thought, or liable to change.
(of education) concerned mainly with broadening a person's general knowledge and experience, rather than with technical or professional training.
noun: socialist; plural noun: socialists
a person who advocates or practices socialism.
synonyms: left-wing, progressive, leftist, labor, anti-corporate, antiglobalization;
"To secure for the workers by hand and by brain the full fruits of their labour and the most equitable distribution thereof as may be possible through the common ownership of the means of production, distribution and exchange."
A reasonable answer to the question what does a socialist believe.
Liberalism is a far more wishy-washy thing, which means different things to different people and has meant different things at different times. There is the libertarian, laissez-faire liberal who believes there is nothing wrong with capitalism, whereas a radical liberal is one who thinks capitalism has major flaws and is for social justice.