Email migration is a process in which a large number of email messages are transferred from one email account to another email account. In general, email migration is required when you are switching email accounts. The cloudHQ email migration will also transfer all meta-data associated with emails: labels, read/unread status, sender, etc. Our migration tool uses Gmail API and has an average speed of ~10,000 emails per day.
Email forwarding refers to the operation of resending email messages from your inbox to a different email address. It is used when you want to send emails to your CRM, colleague, etc. Email forwarding will not preserve email meta-data (such as labels). It also uses Gmail sending capabilities, so it is limited to 500 emails/day for free Gmail accounts and 2,000 emails/day for paid G Suite accounts, per Google daily send limits.