The difference is that the Thule HideAway Roll Out Awning # TH490011 is a direct mount which you install with the included hardware while the Thule HideAway Roll Out Awning # TH490010 is a roof rack mount and it requires a roof rack for the installation.
Other than that they are the exact same awning. view full answer...
You linked to the Valterra EZ Valve Electric Waste Valve for RV Black Water Tank, # E40-8 a 3" Hub to 3" Spigot.
The difference between a hub connection and a spigot connection is that the hub is the female end and has a lip on the inside that stops the spigot (or male) end. Please note the three options of a 3" Hub to 3" Hub - # E40B-8, 3" Hub to 3" Spigot - # E40-8 or 3" Spigot to 3" Spigot - # E40A-8.
I suggest you remove the current component and examine what you have.
For installation,... view full answer...