Microsoft uses standard level definitions to indicate the difficulty level of a course or material they publish. Each is explained below for reference (taken from ieitpro's TechNet Blog).
Level 100 Description:
Introductory and overview material. Assumes little or no expertise with topic and covers topic concepts, functions, features, and benefits.
Level 200 Description:
Intermediate material. Assumes 100-level knowledge and provides specific details about the topic.
Level 300 Description:
Advanced material. Assumes 200-level knowledge, in-depth understanding of features in a real-world environment, and strong coding skills. Provides a detailed technical overview of a subset of product/technology features, covering architecture, performance, migration, deployment, and development.
Level 400 Description:
Expert material. Assumes a deep level of technical knowledge and experience and a detailed, thorough understanding of topic. Provides expert-to-expert interaction and coverage of specialized topics.