1.风险:It is a noun in Chinese.
It means a hazard or risk which probably occur.
ex.If you want to do so ,there will be some "风险"。
ex.We will take a big "风险" to do this surgery。
2.冒险:It is both verb and noun in Chinese.It means do something in spite of jeopardy.
as a verb,冒险=take a risk or run a risk
as a noun.冒险=adventure
ex.没人敢冒险(.verb.)背叛他。(No man would risk to betray him.)
ex.我们在听他讲他的冒险(noun.)经历。(We are listening to his adventures .)