What Is The Biggest Difference Between RHEL And SUSE Linux Enterprise?

Full disclosure: I am an employee of SUSE.

I'd like to respond to something Nicolas Olszowski mentioned in this thread: he asserted that SUSE "[has] been have a lot of financial problems..." but there is no basis for this.

The annual reports of Micro Focus clearly showed that the SUSE business unit was doing well, growing in revenue, and able to make strategic acquisitions (openAttic from IT-Novum and several technologies from HPE Software).

Further to the point: MicroFocus International purchased Attachmate Group (owner of the SUSE brand, as well as Novell, NetIQ, and Attachmate) in 2014 for $1.2B in shares ; just 4 years later, SUSE was split out from that group and made an independent company by EQT, and the value of SUSE alone was $2.5B .

So I don't think it's fair to characterize it as "less commercially astute" .

Both distributions have similar pricing strategies. RHEL and SLES support many of the same architectures, including ARM64, x86-32, x86-64; and Power Architecture, and they are both suited for servers, mainframes, and workstations.
SuSE linux administration is a bit easier than RHEL because of the YaST. in other aspects they are very similar to each other.

Both are excellent, but the decision is related about what the customer wants to do, means their project.

Examples
If customer is developing with app servers based on Red Hat Technologies, the recommendation is Red Hat.
If you are migrating from Oracle Linux, then the option is Red Hat.
But if customer has a SAP Project then SLESforSAP from Suse is the right path.
If you are looking for a POS Linux to deploy a project in retail, then SLES from Suse is the best option

At the end it´s depend of the project both have zones were they dominate, but still Red Hat has more market share than Suse.

Red Hat was just bought by IBM and are the de facto supported distribution
with what I guess is 70% or more market share.
They are strong and are seen as the open source inventors although Linux is
maintained by a community including various other companies
- that said strangely enough they have a very proprietary approach to
their customers and tie them into hard contracts and an all or nothing
clause as well as automatic renewals. They have managed to create a
successful opensource + commercial model

Suse is the German version and will probably be used more in Europe,
especially in Germany. They have been having a lot of financial problems
and have
been sold and bought to VC companies a couple of times.Less commercially
astute I would guess.

Despite no longer being with Oracle that is the distribution I would
recommend as the model is open, no tying the customers down as RHEL, Best
security
features and a big financial backer in Oracle...

It really depends on the requirement of the business. All of linux administrators of every industry know that most of upstream linux's package are from Debian. And RedHat leverage Fedora, SuSE do it through OpenSuSE. Then they packed them through their way such as SUSE go with Autobuild process. In the application level, Most of SAP are running on SUSE. But most linux applications are running on RedHat. In the management level, RedHat had Satellite, SuSE had SuSE Manager which are both built from Spacewalk. In the security level, they do most the same thing from CVE and the each advisory channel.
But worth to know is that along with MicroService and modern application model, RedHat bet OpenShift and 3scale and has it's JBoss platform to construct the new service ecosystem. It's really better then SuSE's CaaS in the ecosystem.
Another consideration is that SuSE comes from a very serious QA process, and drivers/functions backport to meet the enterprise's requirement, so if your business is the `long stay' application in your datacenter or IT environment, you may wish to bet on SuSE solution. Because SuSE's server is more stable than other distro which is base on our past experience.