Although it isn't mentioned in the in-game description, the Scaldis is unique among the XL freighters in one way - it is the only one equipped with Mining Turrets. It is possible that Egosoft intended for the Scaldis to the a dedicated XL-class mining vessel, but forgot to mention it in its in-game description. It is also the only XL freighter to have compartmentalized storage (despite having a "Universal cargo" tag in-game), which gives it some advantage in inventory management if assigned to a station (it won't fill up on just one ware type).

<Info from Simoom's guide: XR Capital Ships>