A spore syringe contains spores. A liquid culture contains living mycelium that has already germinated from spores. One is a reproductive cell in suspension, the other is an organism already growing.
Multispore syringe. Spores from a print, suspended in sterile water. Carries the full genetic spread of the parent, so every spore on your slide is potentially slightly different. Long shelf life refrigerated.
Isolated spore syringe. Spores from a line that has been taken down to a single stable phenotype. Far more uniform on the slide, which matters if you are measuring rather than browsing.
Liquid culture. Living mycelium in a nutrient solution. Genetically uniform because it is one organism, colonises quickly, and has a shorter usable life than spores because it is alive and consuming its medium.
Spore print. Spores deposited dry onto foil or card. The longest-lived format of all and the easiest to store, but you have to make a suspension before you can do anything with it.
This is where UK buyers get confused by American guides. In the United States you can find liquid cultures of Psilocybe species offered openly. In the United Kingdom you cannot, and the reason is straightforward.
A liquid culture of a psilocybin-containing species is living mycelium of that fungus. Under the Misuse of Drugs Act 1971 as amended, fungus containing psilocin is a Class A drug whether or not it has been prepared. Spores are not, because they contain neither compound.
So in the UK: spore syringes of Psilocybe species, yes, for microscopy. Liquid cultures of those same species, no. Liquid cultures of gourmet species such as lion's mane or oyster, yes, and sold for cultivation because they are food crops. That is exactly why MycoWorld's liquid cultures are gourmet only.
For spore microscopy, a spore syringe, and an isolate if you want uniformity. That is the only format that contains the thing you are trying to look at.
For cultivating a gourmet species, a liquid culture, because it skips germination and colonises faster.
For long-term storage of a reference genetic, a spore print.