Teacher's Highland Cream & Teacher's 50
This should help you - info directly from Beam Global Spirits & Wine, Inc. The main difference is that Teacher's 50 is 12 years old whereas Teacher's Highland Cream is a standard blended whisky – no age declared on the label.
Teacher's 50 was developed for the 50th anniversary of India’s independence. It was initially proposed that the blend be made up from a 50:50 mix of malt and grain and that it has at least 50 different single malts would have been bottled at 50%alc. The 50% was not allowed by the Indian government so the company just used the 50% malt and 50 different malts.
The current blend is still 12 yr and has 50% malt, but I think that the number of single malts has had to come down due to lack of stock.
As far as the taste profile is concerned, because Teache's 50 is a 12yr, it is much smoother and softer and because of the 50% malt - much fuller and mouth filling in flavour than Teacher's Highland Cream.