A two-thirds Council of States resolution first: Article 312 and the all-India services
Background
Article 312 is the route by which a new all-India service can be brought into being. It opens only after the Council of States passes a resolution backed by at least two-thirds of the members present and voting, stating that such a service is necessary or expedient in the national interest. Parliament can then make a law creating one or more all-India services common to the Union and the States, and regulate recruitment and conditions of service for them. An all-India judicial service is named in the Article as one that can be created in this way. The two services that existed when the Constitution came into force, the Indian Administrative Service and the Indian Police Service, are treated as having been created by Parliament under this Article. An all-India judicial service cannot include any post below that of a district judge as defined in Article 236. A law setting up such a judicial service can amend the sixth Chapter of Part VI where that is needed, and such a change is not counted as an amendment of the Constitution for the purposes of Article 368.
In plain words
All-India service A service common to the Union and the States — Its officers are recruited centrally but serve both the Union and the States.
IAS Indian Administrative Service — One of the two services Article 312 treats as already created by Parliament.
IPS Indian Police Service — The other service Article 312 treats as already created by Parliament.