Nach holiness

There is actually a discussion amongst the halchic authorities if the Neviem prophets are holier then the Ketuvim writings
The practical ramifications is one allowed to place one on top of the other
Meaning one is a allowed to place a chumach on top of any other sefer yet one is not allowed to place any other sefer on top of a chumash
Some hold that they are equal holiness and for that reason one is allowed to place one of them on the other and vice versa.
While others hold that the prophets are Holier (yet some of those opinions hold that nonetheless one may place one on the other – as the difference isn’t to substantial unlike torah which is much holier and therefore must always be on top).

Addendum
Seforim Piles
If I see a pile of seforim with a Chumash at the bottom, am I obligated to rearrange it?
One may not place an object with less kedusha upon an object with more kedusha. For this reason, all seforim including Nevi’im and Kesuvim may not be placed on top of a Chumash. Torah Shebaal Peh may not be placed on Torah Shebiksav and talis (or tefilin) may not be placed upon a siddur. Some differentiate levels of kedusha within Torah Shebaal Peh itself (e.g. rishonim on Gemara) but this stringency has not been accepted. The Rebbeim treated a Tanya with the same sacredness as a Chumash.
The status of a siddur is questionable: Some say that is equivalent to Nach because it contains many pesukim inside the tefilos (and often has a Tehillim appended to it), while others consider it a new entity of Torah Shebaal Peh. Therefore one should not put Torah Shebaal Peh on a siddur.
Rishonim discuss making a sefer compiled of texts of with various levels of kedusha (e.g. Torah and Nach in one volume). Some deemed it inappropriate since when learning the end of the sefer the middle will be on top of the front. However the majority of rishonim argued that this does not constitute a disgrace since it’s a new entity, and this is the accepted halacha11 (this is the basis for the Chitas).
If one notices seforim piled on a Chumash many poskim say that one is obligated to rearrange them, though there are those who are lenient. The Rebbe would often take notice of stacks of seforim on his way into shul and stop to remove a sefer placed incorrectly.
Some poskim add that when returning seforim to the shelf one may lechatchila pile them up in haphazard manner since he is in the midst of caring for the seforim’s honor.
Sources for the addendum