What is the difference between: Store device data (data roll-ups) Store Device data (raw data retention)

Store Device Data *per account (data roll-ups)
Remote Manager will retain roll-ups for each DataStream within set limits depending on your edition. The amount specified in the Edition Summary is the maximum amount of time Remote Manager will retain data without purchasing additional data retention add-on bundles(s), which are available in 6 month increments
. Customers may configure the roll-up data retention TTL to less than this time if they wish.
 
Store Device Data *per account (raw data retention)
This is the maximum amount of time Remote Manager will retain each data point without purchasing additional data retention bundles. Customers may configure the raw data retention TTL (Time To Live) to less than this time if they wish.
 
In other words:
The sensor takes a temperature measurement every minute and uploads it. That is “raw data”.

The application wants to be able to graph the last 90 days. There is no need to have the resolution of 60 seconds over 90 days. “rollups” allow the user to request a calculated “average” for every half-hour, hour, day. For example, the average temp for every hour over the last 90 days is still fairly high resolution.

In both the platform and standard tier, you can request “raw” data for the past 30 days, you can request “rollups” (summary data) going back 90 days. For Premier Tier accounts, but raw data and rollups are for 6 months.  
Again, the retention times for any tier can be extended in 6 month increments with the addition of add-on bundles in 6 month increments.