An Individual Site collection offers following :
For the Users:
Dedicated Recycle bins
Dedicated usage Reports
Distributed administration (site collection administrators)
Dedicated search scopes, keywords, and best-bets
Custom feature deployments
Dedicated language translation maintenance
Dedicated galleries for web parts, master pages, content types, site columns, site templates, and list templates
Dedicated shared libraries, such as site collection images and site collection styles
Dedicated real estate (Self Containment)
For the IT Administrators:
Site quota templates
Distributed administration
Site locking
Database maintenance options
Backup / Restore abilities
Content Deployments
InfoPath forms services global template targeting