They are not the same; here is Wickipedia's answer:

The terms "mushrooms" and "toadstools" go back centuries, and were never precisely defined, nor was there consensus on application, except to say that the term "toadstool" was generally, but not exclusively, applied to poisonous fungi.

For an example of early usage see Badham (1863. Reference was made to "tadstoles", "frogstooles", "frogge stoles", "tadstooles", "tode stoles", "toodys hatte","paddockstool", "puddockstool", "paddocstol", "toadstoole", and "paddockstooles" from 1398-1597, sometimes synonymous with "mushrom", "mushrum", "muscheron", "mousheroms", "mussheron", or "musserouns". The term "mushroom" and its variations may have been derived from the French word "Mousseron" in reference to moss (mousse).

There may have been a direct connection to toads (in reference to poisonous properties) for toadstools.

However, there is no clear-cut delimitation between edible and poisonous fungi, so that mushrooms may be edible, poisonous, or unpalatable, and it makes no sense to not be able to use the term mushroom when stating there are "poisonous mushrooms" which would be an oxymoron statement if the term mushroom could not be applied to poisonous fungi.

The term toadstool is nowadays used in story telling when referring to poisonous or suspect mushrooms. The classic example of a toadstool is Amanita muscaria.

Toads are negative, right?

it`s not mushrom is applied to edible fungii,toadstool to inedible/poisonous fungi.