CC Field:

CC Field in Salesforce is used to define email addresses. It can contain array or list of email addresses.

CC Recipients Field:

CC Recipients Field is used to define contact, lead, and user IDs. It can contain array or list of Contact, Lead and User record Ids.

Reference Article:

https://help.salesforce.com/s/articleView?id=sf.send_email_quick_action_fields.htm&type=5

Same thing is applicable for To and To Recipients and also for BCC and BCC Recipients fields.