What were the main ideas of liberalism and conservatism? What were the common features and differences

What were the main ideas of liberalism and conservatism? What were the common features and differences between them? Express your opinion why in the last third of the XIX century. some theorists of socialism took the path of reformism.

Liberalism is, first of all, freedom of speech, economy, religion, etc. There are reforms here.
Conservatism is the preservation of the values that exist now. Under conservatism, radical reforms are absent.
At the expense of the second part of the assignment, then, in my opinion, the theorists of socialism took the path of reformism because they realized that it was easier to achieve their goal – socialism.