compatibility Leap 42.1 and SLES 12

Is possible to run applications certified for SLES 12 on openSUSE 42.1 Leap without any problem?

I wouldn’t say that in general.
Most packages in Leap 42.1 come from Factory/Tumbleweed (often much newer than the SLE version), only a small percentage were taken from SLE.

In the end it depends on the particular application whether it works or not.

So, in general is not possible to expect, that app certified for SLES12 will be fully compatible with openSUSE 42.1? I think, that “hybrid distro” based on SLES 12 should fulfil this requirement. May be I miss something important about Leap 42.1…

No.

I think, that “hybrid distro” based on SLES 12 should fulfil this requirement.

Why?
As mentioned, most packages come from Factory/Tumbleweed, not SLE.

If an application is certified to run with a certain package in SLE, you cannot unconditionally expect it to run with the much newer one from Tumbleweed.

But again, it depends. glibc for example does come from SLE e.g.
Qt5, KF5, GTK3, or things like that do not.

If you want to have the guarantee that an SLES12 certified application works, use SLES12 I’d say.

May be I miss something important about Leap 42.1…

Maybe.
The main point is to have the core being maintained by SUSE, and therefore (hopefully) increase the stability, or at least decrease the maintenance burden a bit.
Of course exactly this hybrid approach also caused problems in the first place…

OK … I saw some presentation about Leap 42.1, where was mentioned, that due to the fact, that leap 42.1 is based on core of SLE12 is guaranteed some level of compatibility between SLE 12 and leap 42.1. on applications level.

I just trying to clarify what level of compatibility users can expects.

Yes, some level of compatibility.
But it is not guaranteed that all will work without any problems.

I just trying to clarify what level of compatibility users can expects.

As I said, it depends on the application (and what libraries it uses).

I’m not sure though what “certified for SLES 12” means exactly.

E.g. SLES 12 doesn’t even contain KF5 at all, so an application “certified for SLES12” probably cannot rely on it anyway (although KF5 is a bad example because it should be upward compatible, i.e. there should be no problem running applications built with 5.14 on 5.15 e.g.)

LSB compliant applications should work in any openSUSE version though.
The compatibility to SLES12 is at least a bit better than in other openSUSE versions I suppose.