ESE

The Indian Railways will now recruit officers through the IRMS exam, and only the prelim stage will be common to the UPSC CSE; the other two stages have separate exam structures. Both ways are good; if you want to join for generalist positions through IRMS, CSE is better, whereas if you want to become a specialist, ESE is better.
1. Salary: Both services are group "A" services with an equal salary structure as per the seventh pay commission.
2. Nature of work: The IRMS's work is to look after management in the railways, whereas ESE includes branch-specific work such as mechanical engineers in the railways, who will work in the Mechanical Engineering Division of the Indian Railways.
3. Exam: Through CSE, you will be required to appear in the common preliminary. The CSE prelim syllabus is significantly larger than the ESE prelim syllabus. The questions in CSE are more general than those in ESE, which will be more technical in nature. In addition, unlike ESE, which is branch specific, you can select your optional for IRMS in main.
4. Career advancement: The promotional scale is similar, but you will have more diverse work opportunities in IRMS, unlike ESE.