ConnectLeads will enable you to get Facebook Lead Ads connected with your autoresponder. This means that if someone enters your Facebook Lead Form (enters their email address), their email address is automatically sent into your autoresponder or email software. The focus of ConnectLeads is to collect email subscribers from Facebook onto your email list.
ConnectAudience does – in a way – the opposite. It connects your autoresponder or email software with your Facebook account, so you can create Facebook custom audiences based on who is on your email subscribers’ list (ConnectAudience collects that data from your autoresponder and sends it into Facebook as a Custom Audience). The focus of ConnectAudience is to get more results from the email subscribers that you have.