Generally, tactical refers to attacks on military units (e.g. troops / tanks) so will be shorter range and may be specialized (e.g. anti-ship, anti-tank). Strategic generally references the industry and bases used to support or create military units or even civilian infrastructure (or the ability to wage war), so strategic will be longer ranged and less precise (just need to hit a building etc). Of course, most of the time when people think of strategic missiles they think of the big ones that deliver nukes, but a conventional one that can hit a distant factory is strategic.
Something like a medium ranges missile like the Iskander, Scud or ATACMS is a bit of a crossover, but are normally used a bit more strategically (hit a ammo dump or airfield), than tactically (blow up a bridge). Even an attack on an ammo dump could be argued to be strategic or tactical.
You can use strategic missiles / weapons tactically but it generally only useful for large concentrations of troops etc. The US tried to use strategic bombers a few times in WWII with less than great results. They bombed troop concentration after D-Day in close support of troops but eneded up bombing some of their own units. Level bombers where used to attack the Japanese fleet in the battle of Miday, but had no effect (very hard to hit a moving ship with a stick of bombs)
It is interesting to bring up the cost of the attacking missiles. A quick search comes up with some interesting numbers:
The Kh-101 missile costs $13 million, a Kalibr $6.5 million, an Iskander $3 million, an Onyx $1.25 million, a Kh-22 $1 million, and a Tochka-U $0.3 million'
https://www.ibtimes.com/putin-consigns-russia-poverty-8-cruise-missiles-hit-ukraine-cost-moscow-100m-3597338
Which really puts some of the costs in perspective, especially when you talk about launching million dollar Patriot missile to shoot down a 3 million dollar Iskander (which is what it's most likely / useful to be used for).
The article noted above talks about how a large cruise missile attack Russia did back in August likely cost 91 million for 8 hits. As the Ukrainians start shooting down a larger percentage, the numbers start to get pretty silly and maybe hard to justify (?)