Article 35 A - (The Article doesn’t find mention in any of the bare text of Constitution published in INDIA, including the one kept in the Parliament)

Saving of laws with respect to permanent residents and their rights. — Notwithstanding anything contained in this Constitution, no existing law in force in the State of Jammu and Kashmir, and no law hereafter enacted by the Legislature of the State -

(a) defining the classes of persons who are, or shall be, permanent residents of the State of Jammu and Kashmir; or

(b) conferring on such permanent residents any special rights and privileges or imposing upon other persons any restrictions as respects—

(i) employment under the State Government;

(ii) acquisition of immovable property in the State;

(iii) settlement in the State; or

(iv) right to scholarships and such other forms of aid as the State Government may provide,

shall be void on the ground that it is inconsistent with or takes away or abridges any rights conferred on the other citizens of India by any provision of this part."

So Firstly deciphering the provisions of Article 35A, it is clear that it gives special rights to the "permanent residents" of the state where it empowers the state legislature to define permanent residents and then give them special treatment, privileges and rights. This special treatment is with respect to 'employment with the state government, acquisition of immovable property in the state, settlement in the state, or right to scholarships and such other forms of aid as the state government may provide'.
Secondly flipping through the pages of constitutional history of India we find it intersting to note that this provision was enacted by a Presidential Order in 1954. Presidential Orders are issued with respect to the state of Jammu and Kashmir under Article 370, which is a temporary provision in the Constitution as discussed earlier.

Hope this clears the difference between them, also recently there have been various opinions and thoughts regarding necessity of these articles in todays’ time when “integration of Jammu and Kashmir fully into India” is one of the top priorities of the current government.