How do you tell that a specific bowl will fit into a specific downstem.

So I want to buy a bong, but I would also like to buy a better bowl attachment for it, and i'm using a different website for the bong and another one for the bowl (buying online), and I'm wondering how do I tell if the bowl will fit correctly?

My bong's specifications (measurements);
(the bong comes with an ash catcher, but i want to replace the ash catcher attachment with a bowl
Downstems : 5" / Ash catcher Joints (14mm) / Neck Joints (18 mm)
...
And the bowl's specifications:
- Joint : 14 mm

so would this bowl fit the bong's diffuser? and witch measurements have to match the bowls (ash catcher joint, or neck joint?)

Thank you.