Free vs. Pro: What is the difference?

Does Free have unlimited subscribers?
Yes, it does.

So it's unlimited Free plan just with limited functionality? 
Yes, it's unlimited in terms of subscribers but with a limited number of Growth Tools, Sequences, Autoposting channels, etc.

What extra features do you get with Pro? 

Remove ManyChat branding from Messenger and Main Menu, Unlimited Automated Sequences, Customizable Growth Widgets, Unlimited Tags, Filters and Segments and more.

Check out our Pricing page to see the difference.

Hope that helps.