im no expert but from what i can recall i thought they where the same thing. for the fittings still holding up. i personably dont have it, i made it for my friend and its still under his 75gal reef tank. the only way i can tell that it has worked out well for me and him is that i have never changed a filter or carbon or any other filter media. thats really why i got into using fuges as my filtration.
p.s. for the box i built i didnt use silicone. i got this stuff from my local glass shop, its some sort of glue that fuses the two pieces together. if the two pieces are cut flat and cleaned up the bond is stronger than the plexiglass itself.
HTH if you have any other questions im more than happy to help.im also in the process of building a larger one for my buddy. he wanted a bigger refugium so now im using a 29gal. will have pics when i start.