There are classic resins in miniature modelling (used for decades) and new resins (used for around the decade).
Classic resins are mostly very hard and keep perfect detail. They are super miniature medium differing to metal in two aspects:
They are brittle not bendy so when dropped could break in parts.
Second aspect is they are much more difficult to strip as most stripper agents can wash out some elements of the resin itself and make it gummy (destroy it mainly).
Some parts may by bent but are easily reshaped with use of hot water or hairdryer. This is the kind that produces toxic dust when worked.
Many companies do miniatures from this medium. Some whole - Forge world, some partially - Battlefront.
Great most of mentioned small run and limited run companies, especially in larger scales and bust are made from resin.
Best visible in Hasslefree page - They are offering thei models in metal ad in resin at the same time - better detailed and twice the cost.
https://www.hfminis.co.uk/Newer kinds are more bendy than brittle. Some miniature companies started to use it with different levels of success.
To be honest GW Finecast was worst kind Ive seen of it.
They are hard to damage but very easy to cut and convert (softer than plastic) - they are kind of plastic resin hubrid.
Minus of this is bendiness - different in different kinds/producers and returning to shape.
When you have warped Finecast miniature and straighten it with hot water or hairdryer it can bent to original warped state by just sun exposition (quite low temperature).. or just under its own weight
This guy (in the middle) is jumping and touches the base with scabbard only.. Mine will bent to front to an unusable degree after around 4 weens under its own weight.. Whatever I would do.. It always returns to warped shape ( i had to cut him and use heavy pins and GS)
But as I said Finecast was worst kind of neo resin Ive seen so other companies products are better and this effect is visible only on some miniatures - heavy and badly designed with weight support and distribution.
Bones material is kind of this - bendy but usable and worls well. But removal of lines of molding is very difficult due to elastic softness of the material.
All of them are perfectly well usable in gaming but you have to be careful with hard resin as its more delicate than metal or plastic.