the 3501 is the higher viscosity ( goo ) in the tube .

the 3502 is the lower viscosity liquid in the small jar that is applied via capillary action .

Both for polystyrene used for plastic model kits .

( 3503 is for wood  , supplied in tube  .  3505 is for wood / metal  , also supplied in tube )

3509 ( blue label  , goo in tube ) can be used for polystyrene but also ABS

I prefer using the low viscosity glues for their capillary flow application  ( 3502 Testors  , Tamiya Extra Thin  or similar : https://www.scalehobbyist.com/catagories/Paint_and_Construction/browse.php?s=4&t=2&u=0 )

Hobby Lobby has the Tamiya and Testors if you have one nearby .

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