今天才知道SLES（SUSE Linux Enterprise Server）和SLES SP（SUSE Linux Enterprise Server Service Package）是不同的版本，SLES相当于主版本（major version），而SLES SP则相当于基于主版本发布的小版本（minor version）。参见wiki百科：
SUSE Linux Enterprise Server (SLES) is a Linux-based operating system developed by SUSE. It is designed for servers, mainframes, and workstations but can be installed on desktop computers for testing as well. Major versions are released at an interval of 3–4 years, while minor versions (called “Service Packs”) are released about every 18 months. SUSE Linux Enterprise products, including SUSE Linux Enterprise Server, receive more intense testing than the openSUSE community product, with the intention that only mature, stable versions of the included components will make it through to the released enterprise product. SLES 11 SP4 was released July 16th, 2015, which is developed from a common code base with SUSE Linux Enterprise Desktop and other SUSE Linux Enterprise products.
查看SLES发行版信息：
linux-6fj5:/ # cat /etc/issue
Welcome to SUSE Linux Enterprise Server 11 SP4 (x86_64) - Kernel \r (\l).