Group B services can be equated with state civil services. Officers for Delhi as well as union territories are appointed through this service. The careers of officers in Group A service is equivalent to those in the top Indian services- they do not enjoy that much power though. IAS is the strongest service when it comes to powers the officers hold. But this is not the case with Group B service. There is a major difference in the careers of officers from Group A service and those from Group B service. But this service is still preferred because it isconsidered better than other government jobs.
Friends, I have tried to give you a brief but essential description of all the services that fall under civil services. The purpose of this was to make you aware of the actual nature of the services because I have seen that the youth, especially those who tome from far off towns and cities are not aware of the services. That's why they face problems when listing down their preference and sometimes they do not give preference at all. They may have to regret this later on. I'm not claiming that my telling you this will solve your problem 100 percent, but you will at least be aware of the facts. I would suggest you collect information about various services while preparing for IAS. It will help you set your preferences right.
Friends, you may think in the beginning that how does it matter whichever job you get, at least it's a job, but you will repent this. Do not take the preference of the services lightly. You may get any service but every service comes attached with its own policies, culture, prestige and comforts, and in a sense this becomes our lifestyle, So you should give your preference after giving this a serious thought.