Ok so this is my current understanding, please correct me where I err and supplement where I omit needed information.
Historically the Mensheviks and chartists inspired social democracy whereas the Bolsheviks inspired Marxism-leninism.
They (demsoc and socdem) are extremely similar but have some key differences. Social democrats are to the right of democratic socialists and they are both centre-left parties slightly to the left of social liberalism.
left-ish------Center-left----Center
---------Demsoc-----Socdem Libsoc Lib
Where they differ is usually on imperialism and capitalism.
Social democrats typically support imperialism continuing so long as a slice of the spoils support a welfare state. In that sense they're just capitalist reformists. It also appears that the DSA and the "Democratic-Socialist" movement in the United States is simply social democracy with no intention of seizing the means of production.
Democratic socialists do advocate for seizing the means of production and want the end of imperialism but believe this can be accomplished democratically -- however naive that may be.
As far as I can tell social liberalism appears to be almost synonymous with social democracy but with an added emphasis on the "freedom" to own private property and a more laissez-faire role of the state.
Please fill in my understanding :)
Democratic socialism and social democracy are basically the same thing. Both are trying to achieve "socialism" by reforming the liberal apparatus. The problem is, their strategy maintains the capitalist juridical superstructure intact, which is private property. If they ever try to get close to abolishing private property through reform, they will face fierce resistance from the bourgeoisie, who will try every tactic to undermine them. But since they adhere firmly to the liberal institutions, they will always retreat or be defeated.
I would call social liberalism, a even worse tendency than socdem, and this is our current hegemonic left throughout the western world. It's basically a socdem tendency that chose to adopt neoliberal institutions as sacred. Figures like Tony Blair, Keir Starmer (or basically the British labor party), Cristina Kirchner, Boric, Lula, the current German SPD, and the US Democratic party are examples of social liberals. They are worse because they aren't even reformist parties. They are basically conservatives who advocate for a few social policies, but who try to maintain the neoliberal counter-reforms at all costs. They are all adepts of austerity policies, privatization, and the neoclassical interpretation of (political) economy.
The social liberals are the reason why the workers are siding now with the far right in droves, throughout the whole world. The workers don't see themselves represented by the social liberals because they don't offer any meaningful change for them. They are going for the far right because they started adopting an anti-systemic rhetoric. If fascism rised after WWI as a response against socialists and communists that gained strength, the new fascists have risen from the weakness of social liberals.
And recruit workers to their purpose by keeping them ignorant of the difference between personal and private property. This is a huge sticking point.