It depends on how you look at it. Step 1 tests more concrete information and basic pathophysiology that comprises the traditional medical preclinical curriculum: Anatomy, Physiology, Pathology, Pharmacology pertinent to all Organ systems. This information is, by and large, immutable. For example, understanding that Von Gierke's disease (GSD Type I) results from a deficiency in glucose-6-phosphatase is not going to vary from year to year. Step 1 is predicated upon fixed, knowable information. Moreover, the sheer hysteria that surrounds Step 1 performance has set a high bar for excellent preparation, meaning that there are some very quality resources out there for studying: USMLE Rx, FA, UWorld, Kaplan, etc. The test, though challenging, is conquerable if you put the study time in.
I personally found Step 2 to be more challenging, despite the fact that scores on Step 2 are usually higher on average than for Step 1. This is because Step 2 often tests what the "next best step" is in terms of workup or treatment; unlike basic science facts, this information DOES vary from year to year. External study resources like MTB can quickly become outdated if not published annually. The sheer breadth of information covered by Step 2 is much wider as well. On both Step 1 and Step 2 exams, you will encounter questions the likes of which you have never seen before, or test disease processes that you are unfamiliar with. However, I had far more of those "WTF is this?" type questions on Step 2 than I did on Step 1.
Nevertheless, this is all countered by the fact that most people take Step 2 after completing their third year clerkships, when they have seen many of the things tested by Step 2 first-hand on the wards. While I don't think the Step 2 exam is actually any easier than Step 1, I suspect that the experience of M3 reinforces learning this material better than studying from books.