Are Kaplan Questions Harder than Acheviable Questions?

Got the Kaplan QBank to supplement Acheviable Questions. With Acheviable questions I easily get 80-100% of the questions right. But with Kaplan its like 55-70%. Like it feels like im encountering things I haven't see before like M2 and M1 for Federal Reserve. Should I stick with the Kaplan QBank feels like its hurting my confidence rather than building it up?