Discrepancy in storage space on SSD

[ImpatientSpade]

I've noticed when installing software there is a discrepancy between the amount of storage space I have available on my SSD (see image). Does anyone know why this is or what is causing it?

Thanks in advance!

 

[Weaselboy]

http://support.apple.com/en-us/HT202301

You have Time Machine turned on? That creates local snapshots that are shown in one and not the other storage readout there.