The security council is one of the most common specialized committees. It is comprised of 15 delegations, 5 of which are permanent and 10 are elected with two-year terms by region. The 5 permanent members (aka the Big 5) have veto power, meaning they can veto any resolution regardless of the other votes in committee. The Big 5 are China, Russia, France, the United Kingdom, and the United States, and were chosen because of their victory in World War 2. The security council rules on the most assertive United Nations actions including but not limited to enacting or lifting sanctions and deploying peacekeepers.
While it may appear as though you have less power, you have a lot more flexibility in your role. Other members of the Big 5 already have previously established groups they divide into (China and Russia vs France, the United Kingdom, and the United States) that your delegation doesn't always automatically fall into. As such, you can often befriend more members of the Big 5, meaning that your resolution is more likely to pass as they are less likely to veto your resolution. The other nations also have a big impact on what gets discussed and can easily influence the Big 5 members.
The security council has more specific jurisdictions than the general assemblies, especially since the general assemblies resolutions are guidelines whereas the security council resolutions are commands. The following is a list of powers and responsibilities that the security council has:
to maintain international peace and security in accordance with the principles and purposes of the United Nations;
to investigate any dispute or situation which might lead to international friction;
to recommend methods of adjusting such disputes or the terms of settlement;
to formulate plans for the establishment of a system to regulate armaments;
to determine the existence of a threat to the peace or act of aggression and to recommend what action should be taken;
to call on Members to apply economic sanctions and other measures not involving the use of force to prevent or stop aggression;
to take military action against an aggressor;
to recommend the admission of new Members;
to exercise the trusteeship functions of the United Nations in "strategic areas";
to recommend the appointment of the Secretary-General (the person who oversees UN operations) and, together with the Assembly, to elect the Judges of the International Court of Justice.