The STX range is the ecomony ("street performance") line with minimal adjustment (just rebound):
https://www.ohlins.eu/en/products/motorcycle/ya-419--4779/
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Whereas the S46HR1C1S is higher end ("Road and track") and features a remote reservoir as well as adjustable compression damping and easier to operate on the fly hydraulic preload adjuster:
https://www.ohlins.eu/en/products/motorcycle/bm-048--3898/
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I believe the STX product is overpriced for what it is, when you compare it to something like the Nitron R1 which has at least the same functionality and comes custom built for your weight and general usage:
http://www.nitron.co.uk/catalogue_item.php?catID=12992&prodID=76735
(Thery also offer higher end R2 and R3 products)