Changes described somewhere:

1)
In WMS 1.1.1, there were “stubs” for SLD in the specification text and schema. The SLD spec defined what to do with those stubs.
In WMS 1.3, those stubs have been removed, and now it is the job of the SLD spec to normatively reference and extend the WMS specification.
The forward dependence of WMS on SLD was removed during the WMS ISO 19128 standardization process (source: http://lists.eogeo.org/pipermail/wms-dev/2005-January/000691.html)

2)
This typing issue is a problem with the WMS 1.1.1 specification. The specification ridiculously specifies a mime type other than text/xml for the returned XML content, so unaware applications receiving the content treat it as an unknown content type. Your programs can work around this, but web browsers typically don’t. The problem is expected be corrected in the WMS 1.3 specification (source: http://www.codeproject.com/csharp/WMSOverviewAll.asp)

3)
Differencies in CRS –> In WMS 1.3.0, this is indicated by the line within a Layer definition in the Capabilities XML, which becomes
&CRS=CRS:84&BBOX=minLongitude,minLatitude,maxLongitude,maxLatitude in the GetMap query to the server. In WMS 1.1.1, the syntax is somewhat different, becoming
&SRS=EPSG:4326&BBOX=minLongitude,minLatitude,maxLongitude,maxLatitude
(source: http://svs.gsfc.nasa.gov/documents/arch_6.html)

and 4)
The “vocabulary” attribute was introduced in WMS 1.3.0 and is not available in WMS 1.1.1 (source: http://svs.gsfc.nasa.gov/documents/arch_7.html)

“OGC staff responds: OGC has worked with ISO for many years. The OGC members agreed to release WMS to ISO to be approved as an ISO standard. The OGC and ISO had a joint edit team that worked on WMS resulting in IS19128:2005 which is identical to WMS 1.3. Each organization has its own vision and process. While we understand that some documents seem to take quite a while to be approved, we also believe that input from ISO to OGC and from OGC to ISO has been most valuable in creating the best standards possible.”