Office365 OptionsOffice365 has many options and it can be confusing on their web site. Here's an easy to read all-in-one page to quickly identify your needs:
| EXCHANGE-1 | EXCHANGE-2 | OFFICE-365-ESSENTIALS | OFFICE-365-BUSINESS | OFFICE-365-PREMIUM | OFFICE-365-PROPLUS | OFFICE-365-E1 | OFFICE-365-E3 | OFFICE-365-E5 | |
| cost-montly | $4.00 | $8.00 | $5.00 | $8.25 | $12.50 | $12.00 | $8.00 | $20.00 | $35.00 |
| cost-annual | $48.00 | $96.00 | $60.00 | $99.00 | $150.00 | $144.00 | $96.00 | $240.00 | $420.00 |
| exchange | YES | YES | YES | NO | YES | NO | YES | YES | YES |
| mailbox-size | 50GB | 100GB | 50GB | 0GB | 50GB | 0GB | UNLIMITED | UNLIMITED | UNLIMITED |
| apps-online | NO | NO | YES | YES | YES | YES | YES | YES | YES |
| apps-desktop | NO | NO | NO | YES | YES | YES | NO | YES | YES |
| onedrive | NO | NO | YES | YES | YES | YES | YES | YES | YES |
| onedrive-size | 0TB | 0TB | 1TB | 1TB | 1TB | 1TB | 1TB | 1TB | 1TB |
| shared contacts | YES | YES | YES | NO | YES | NO | YES | YES | YES |
| shared calendar | YES | YES | YES | NO | YES | NO | YES | YES | YES |
| audio-conferencing | NO | NO | NO | NO | NO | NO | NO | NO | YES |
| maximum users | UNLIMITED | UNLIMITED | 300 | 300 | 300 | UNLIMITED | UNLIMITED | UNLIMITED | UNLIMITED |
NOTES:
- -HOSTED-EXCHANGE Plans are here: https://products.office.com/en-us/exchange/compare-microsoft-exchange-online-plans
- -OFFICE365-BUSINESS Plans are here: https://products.office.com/en-us/business/compare-office-365-for-business-plans
- -OFFICE365-ENTERPRISE Plans are here: https://products.office.com/en-us/business/compare-more-office-365-for-business-plans
- -you can only upgrade from a HOSTED-EXCHANGE plan to an OFFICE365-ENTERPRISE plan.
(You cannot upgrade from a HOSTED-EXCHANGE plan to an OFFICE365-BUSINESS plan.)
See here: https://support.office.com/en-us/article/Business-plans-you-can-switch-to-in-Office-365-7a82c397-a2e2-47ab-b371-39d25a66b582