I have gone through the question very minutely. First and foremost, some of the previous answers are not (fully) factually correct. My responses are as follows:-
(a) You have indicated Grade Pay of the two posts. The concept of Grade Pay has become obsolete after implementation of VIIth Central Pay Commission (CPC).
(b) If you have applied for the new post through proper channel and if both the posts (your present position and the post against which you are going to be appointed, if selected) come under Central Government, then you will get pay protection.
(c) Now, what is pay protection? It means that in case of your selection and joining the new position, your basic pay will remain same (i.e., you will draw the same basic pay which you are currently drawing).
(d) However, although your basic pay will be protected in your new post, after one year (of joining new position), you will draw increment at lower rate (commensurate with the lower scale in which you will work).
(e) If you have applied for the new post through proper channel, if both the posts (your present position and the post against which you are going to be appointed, if selected) come under Central Government and if your technical resignation is accepted by your present office, then your previous experience will be counted for the purpose of pension and other pensionary benefits and for the purpose of applying for Government accommodation.
You are welcome to seek further clarifications, if necessary.
Caution: Explosive. Handle with care.