Why is it better?
Zindus – syncronize your gmail contacts directly with Thunderbird
Dictonaries – Speelchecking is a must for me, many languages supported
Contact Sidebar – Easy access to all your contacts
Remove Duplicate Messages – Sometimes my thunderbird downloads the same message twice, or some restore could cause duplicate emails.
Enigmail – Easy encrypt your emails with OpenPGP
Beacuse of its many cool Addon’s , my favorites are:
MozBackup – Easy backup/restore of Thunderbird emails.
Not Addons, but really helpfull: