Space torpedoes are either orbital missiles, stealth ship killers, or interplanetary WMDs
A popular aphorism among navy experts seems to be that missiles cripple, and torpedoes kill.
The one and only meaningful difference between torpedoes and missiles is the medium they traverse. For all intents and purposes, torpedoes are underwater missiles. I see three possible ways to have a plausible semantic shift from naval torpedoes to space torpedoes:
▪︎ From under the ocean to 'down' gravity wells, space torpedoes as dedicated orbital missiles.
▪︎ From silent ship killers to dark spaceship killers, space torpedoes as stealth antiship missiles.
▪︎ From underwater missiles to interplanetary kinetic kill vehicles (IKKVs, nicknamed Hikers or Hiker vehicles) — or similarly powerful weapons sporting nothing short of antimatter warheads — space torpedoes as transmedium missiles (as they depart either from gravity wells to outer space, and back again to gravity wells, or from outer space to gravity wells as part of a strategic strike).
In space, there is no up or down, above or under, nor is there an ocean per se. But there is a topological change between outer space and the vicinity of celestial objects, as spaceships then must deal with the toll on their ΔV taken by massive objects.
This creates two distinct sets of constraints that spacecraft are designed to overcome, however missiles have limited capabilities and a choice must be made. Two categories of dedicated missiles may then exist: missiles with high ΔV, semi-decent thrust and acceleration for maneuvers and boost phases on the one hand; missiles with semi-decent ΔV, high thrust and acceleration to quickly reach escape velocities within gravity wells on the other hand.
These environments and consequent parameters recreate differences analogous to different media, hence the term space torpedoes for the dedicated orbital missiles.
'In space no-one can hear you scream' says Alien's promotional material, which is practically true. However ships are visible from truly astronomical distances if they're bright enough (e.g. when they fire their engines to accelerate/decelerate, or when they use heat intensive energy weapons), which is why stealth can still play a role in space, provided ships are dark enough to blend in against background starlight and radiations until they reach combat ranges.
Underwater, things are reversed, as subs and torpedoes are practically invisible, yet can be heard from long distances, which is why silence is the name of the game, as it's all about reducing sound emissions, sonar reflections, and blending in background noise. Thus our silent hunter killers under the sea may be paralleled in deep space with dark hunter killers, ready to launch dark, rather than silent, space torpedoes, i.e. stealth antiship missiles which would further the analogy and come into two different classes: lightweight space torpedoes, used against our space submarine analogs and launched from just about all platforms, and heavyweight space torpedoes, used primarily by space sub analogs against both warships and cargo ships. Though in this idea space torpedoes are imitations rather than proper analogs for its underwater homonyms.
For the last option we combine the distinction between media traversed with the idea that just like naval torpedoes our space faring analogs could cruise toward their targets, i.e. would be continually self-propelled, vs undergoing acceleration and conserved momentum phases like other space missiles. So they'd be space cruise missiles that happen to traverse both deep space and gravity wells throughout their journey, placing two different sets of constraints that call for designs mirroring more closely spaceship designs than missile designs, minus the crewed part.
Although we might come up with crewed kamikaze IKKVs for the fleet killing and orbital defence killing types, as we may need a human in the loop to 'think outside the box' and avoid wasting warheads that may appear even costlier than human losses. The extreme difficulties of producing an containing enough antimatter to make warheads comes to mind. Other options may obviously be available later in your setting if AI gets good enough to "man" smart IKKVs or antimatter-tipped variants, though combining AIs with fleet killer WMDs might not be such a smart move after all. ;)
[Note that either a crewed IKKV or an AI-piloted IKKV would not only be super hard to trick or take down, but would also dial the stakes up to eleven, while no longer needing delayed guidance from the mothership or the 'not-so-smart' classical self-guidance of missiles. On the pus side, historically there has been a crewed japanese torpedo design, so it's not coming out of nowhere]