Hey Adam, great question! Ocean.io is a paid data provider that uses it's own "similarity score" to find lookalikes. You can also apply much more advanced criteria with ocean.io on the types of lookalikes you find. Ocean.io costs 1 credit per lookalike.
The find companies "lookalikes" searchon the other hand is completely free and does not have as many lookalike filters you can apply. This uses our third party data providers to specifically find lookalike companies based on company attributes and job-related information.
I've included links with more information about both of these actions. Let me know if this makes sense and if you have any further questions!