There were three different developers for the residential buildings in The Well - Woodbourne Capital, RioCan Living, and Tridel. Tridel itself has two different types of building - their Classic Suites (their two buildings on Front Street) and their Signature Series building (the one on the north-west corner of The Well, facing Wellington Street West). The design and construction standards for each building would have been up to the respective developers - the highest quality by far would be the Tridel Signature Series building. So, the obvious and quick answer to your question would be 'It Depends'.
The minimum standard, in order to meet the fire code requirements for unit separation, would result in two walls of double drywall with a gap between them - for a minimum three hour fire protection between units. The gap between the two sets of double drywall should be filled with a sound dampening material - typically fibre glass batting. Unfortunately, even in the best of installations, there will be gaps within the batting material - electrical junction boxes, electrical and communications outlets, etc. Sloppy installation of the sound deadening batting can be a problem, the batting may partially or even completely missing. I do not know of any minimum requirement for the construction of walls within a suite, - it may not even be double drywall.
Another issue - and a building building code requirement - there will be a small gap around the main entry door of every unit, to allow positive air flow into the unit from the building's make-up air flow vents in the corridor. So typically the greatest sources of noise penetration into a unit would be either through the entry door, or through the double drywall areas in which the sound dampening material is absent - either by design (outlets, etc.) or sloppy installation.
In some cases, there may be poured concrete walls, or masonry brick separating units, but I believe that is relatively rate in most new builds these days.
Obviously not an answer to your question, but more of a guide for follow-up questions you may wish to ask regarding the building in which you would be interested.