I downloaded a trial version of PSE9 to show some attendees at a workshop I gave. I may not be commenting from the latest version of ACR for PSE but I doubt Adobe would make significant changes in a couple months.
Like PSE itself, ACR for PSE is, essentially, a feature-stripped version. You get the basic RAW conversion tools but not the more comprehensive tools. PSE ACR has 3 tabs - Basic, Detail & Calibration. PS ACR has 10 tabs - Basic, Tone Curve, Detail, HSL/Grayscale, Split Toning, Lens Correction, Effects (Grain, Vignetting), Calibration, Presets & Snapshots. If you discount the Effects, Presets, Split Toning & Snapshots tabs, PS ACR still gives you much more control over your RAW files than PSE.