Four levels of reading are elementary, inspectional, analytical, and syntopic.

Elementary reading is a basic step of reading which you learn to do in schools. It is when you don't understand what is written and trying to understand word by word. An example is something written in any foreign language you don't know.

Inspectional reading actually has two sub-types- systematic skimming, and superficial reading. Systematic skimming refers to almost everything you read. It is a type of reading in which we need the information urgently but we don't have the time to read it full. For example checking an article. Just checking the heading and sub heading and the introduction just to know the topic and what the article is  about. Superficial reading is the one in which you read word by word without skipping anything. It is used in entertainment and information. For example, reading any book or novel for relaxing.

Analytical reading style is used if you want to understand the topic in depth, as you end up asking many questions about the book you are reading, and you have to organise your thoughts in a systematic fashion. It is a complete form of reading with unlimited time. Understanding the book or novel from the authors point of view if the part of this type of reading.

Synoptic reading is a comparative reading. It consist of reading same topic in many books and compare them. Syntopic reading includes finding the relevant passages ans forming an intelligent opinion by analysing all the information you have gathered.

Hope this helps. Thank you