The Mini-14 Tactical rifles feature a “Improved receiver with rounded contours.”. This improved receiver is also available on some of the standard Mini-14 Ranch Rifle.
From the photos I have seen I cannot see any differences. Ruger has altered Mini-14 many times over the years so this is not a big deal. It would be a big deal if accuracy has also improved.
The Mini-30 and 6.8mm models have not been updated.