What are the similarities and differences between the experiments to create black states in Sierra Leone and Liberia?

What are the similarities and differences between the experiments to create black states in Sierra Leone and Liberia? Why did the first one fail and the second one succeed?

In 1787, a company of English philanthropists bought a small region of Sierra Leone on the west coast of Africa and began an unusual experiment there. At its own expense, the company sent former slaves to Sierra Leone, creating a kind of Negro state for them there. But not all blacks were able to adapt to the tropical climate, most of them died from diseases. At the beginning of the 19th century, the experiment was terminated. Sierra Leone has become a traditional colony.
The fate of neighboring Liberia was more successful. There, in 1821, American opponents of slavery founded the settlement of Monrovia (named after US President James Monroe). Negro slaves were transported there from the United States, freed by their masters, who fled from their master or ransomed by opponents of slavery. In 1847, Negro settlers proclaimed the creation of the Republic of Liberia (which means “free”).