At TheStreet's Investor Boot Camp, Jim Cramer compared 2018 to 2017 -- and said they are "nightmarishly different." 

He said that that it's "day and night...Basically last year, everything worked...this year we need whole set of rules."

He blames the "pajama traders" for a lot of it.  

Excerpts from Jim Cramer's event here:

Learn More about TheStreet's Investor Boot Camp HERE