zcfinput instructs Zesty.io to send an email to the recipient configured in Settings > Instance Settings > Contact Form as shown in the picture below. A common use case for this would be having a contact form that is submitted to your company email, the recipient.
zlfinput instructs Zesty to record the form submission. Then you can view your leads from the Lead section inside the content manager. The Leads section will not be visible until you have captured a lead submission. The value provided in the input is simply for organizing and identifying your forms.
last_nameinput names will be displayed. Every other field will be stored and shown to you on the individual lead view.
https://www.salesforce.com/servlet/servlet.WebToLead?encoding=UTF-8. This means you will by pass Zesty's lead capture feature. One way to send a lead to both Salesforce and Zesty is by using AJAX upon the form submit to post the data to another endpoint.
<input type=hidden name="oid" value="XXXXXXXXXXX">
<input type=hidden name="retURL" value="https://zesty.io/example/thank-you/">
oid: Organization id, which is specific to your Salesforce account.
retURL: As the name implies a url which the user submitting the form will be redirected to after submission.