MIssing internal storage
You didn't name the device, but that's the usual way manufacturers fool their customers without lying: the storage chip has 8GB, but guess where the OS is installed? Looks like on your device, ~4GB are reserved for this (/system). Then there are other partitions on the very same storage chip, e.g. for /recovery and /cache. What's left in the end is /data – storage space available for apps etc. Those are your 3.65GB.

RAM doesn't play a role in this context, it usually goes to a different chip.

For additional details, please take a look at my answer on Android Folder Hierarchy.