Took me a while to figure out. On WP 3.9 with an activate TinyMCE Advanced plugin (v4.0.1) a standard posts wysiwyg field looks like that.
a wysiwyg field from the advanced custom fields plugin (v. 4.3.6) looks that way.
Unsure on which part the root of this misbehaviour sits. just wanted to let you know. if i deactivate the tinymce advanced plugin the toolbars of standard posts as well as acf posts are identical and all works fine. the acf plugin seems just to be unable to get the proper settings from the tinymce advanced plugin. best regards Ralf