Which is more difficult in terms of difficulty?

Organic, because most people think organic is the most difficult. However, physical chemistry and analytical chemistry are also difficult and need a good mathematical foundation. Personal advice varies from person to person.

Material chemistry, analytical chemistry, organic chemistry and polymer chemistry are all very good.

The principle of chemical engineering is more difficult than physical chemistry.

If you take the postgraduate entrance examination, physical chemistry and chemical engineering principles are both chemical engineering courses, and the schools that apply for the exam will give their own questions.

For example:

Taking the chemical industry of Kao Tianda as an example, physical chemistry is a few major problems. They are all types of calculation questions, and the questions are very fixed. Every chapter will have it, as long as you do the exam questions for a few more years. There will be objectives and priorities for review; As for the principles of chemical engineering, knowledge points are widely distributed. Calculation problems are typical. If you don't understand the knowledge thoroughly enough, you will easily get confused and lose your judgment. So as far as the exam is concerned, the principle of chemical engineering is more difficult than physical chemistry. Physical chemistry is abstract in knowledge content. The principle of chemical engineering is more practical and easier to understand, so physical chemistry is more profound.