Conservatism is a cultural, social, and political philosophy and ideology that seeks to promote and preserve traditional institutions, customs, and values.

Liberalism is a political and moral philosophy based on the rights of the individual, liberty, consent of the governed, political equality, right to private property, and equality before the law.

These are just different ways of describing support for the status quo with different flavor modifiers. The core of both is the protection of Capital from any threats from the left (aka socialism, the democracy of the workers, removing power from the owners of capital).

This is why from a leftist perspective, they are essentially the same in that they both are against any actual emancipation of the working class if it threatens the existing power structures of capital owners.