Are the effects of sclerotia truffles similar to magic mushrooms?

Don’t take a huge dose under the mistaken impression that sclerotia truffles are a much weaker version of magic mushrooms! 

The only known active ingredients of magic mushrooms are psilocin and psilocybin, which are also contained in sclerotia. 
The psilocybin gets converted to psilocin before it enters the brain, so the difference in effects between any type of mushroom or sclerotia will depend purely on how much psilocin gets into your brain and the timescale over which this takes place. 
Some types of mushroom (such as the Hawaiian) are very strong and take effect very quickly. In terms of potency, sclerotia are more similar in effect to the Cubensis-type mushrooms previously sold as Mexicans, Columbians and so on. 

Sclerotia take effect noticeably more slowly than mushrooms, but at comparable doses the results are very similar. 
Expectation can play a large part, so if you are told that what you are taking is very visual or more philosophical that can influence your trip.