UPSC

The Union Public Service Commission UPSC administers the Combined Defence Services CDS exam. I assume you want to compare the Civil Service and CDS. Both are reputed government jobs but are unique in the nature of work. Here is a brief comparison given between the two services:
Civil Services:
1. It includes services such as IAS IPS, and IFS. These are responsible for policy making and implementation.
2. Civil servants maintain public law and order. These services are comparatively less adventurous than CDS.
3. It is mostly a non-uniformed service except for IPS and IRS (C&CE).
4. Civil servants mostly deal with civilians and therefore live close to civilian areas.
5. Civil servants do not have perks such as a canteen, but their salary is usually on par with other group A services. CDS:
1. The CDS exam is generally conducted for defence roles in the Indian Army, Airforce, and Navy.
2. It deals with Indian security and therefore is more adventurous. It can directly expose you to the frontline.
3. The CDS is a well-known uniformed service.
4. CDS does not involve much civilian exposure and officers mostly stay in cantonment areas.
5. CDS officers have additional perks, like canteen service. Therefore, both services are good, and it depends on your aptitude to choose which one you want to choose. If you want an adventurous life that directly involves protecting the country, join the CDS. But if you want to work in the service of people, join the civil service, such as the IAS.

The UPSC exam is conducted for around three all-India services, 13 Group A and four Group B posts. These posts are as follows: (a) The posts of all India service
1. IAS Indian Administrative Services
2. Indian Police Services.
3. Indian Forest Service: Only the Prelim is shared for this service; the rest of the Main and Interview are held separately. (b) The posts for Group A:
1. The Indian Foreign Service (IFS)
2. Indian Postal Services
3. Indian Revenue Service (IRS IT)
4. The Indian Revenue Service (Customs and Indirect Taxes)
5. The Indian Defense Accounts Service (IDAS)
6. The Indian Civil Accounts Service (ICAS)
7. The Indian Corporate Law Service (ICLS)
8. Indian Defense Estates Service (IDES)
9. The Indian Information Service (IIS)
10. The Indian Trade Service
11. Indian P and T Accounts and Finance Service
12. The Indian Audit and Accounts Service (IAAS)
13. Indian railway services (Until a separate exam is scheduled. ). (c) Posts in Group B
1. The Armed Forces Headquarters services
2. DANICS
3. DANIPS
4. Pondicherry Civil Service (PONDICS).

If you are referring to the civil services exam, then as per the UPSC calendar 2023, the Civil Services Prelims is scheduled to be held on May 28. So far, there has been no notification of a syllabus change. As per the latest information, the syllabus will remain the same in 2023 for both the prelims and main exams. If there is any change, it will be notified in the month of February in an official notification from UPSC. There may be some changes in the question pattern as seen in the 2022 papers, but they will be minor and will not be made all of a sudden. Therefore, there is no change in the UPSC syllabus for 2023 as of now. If there will be any change, then it will be notified by official notification months before the exam.