HI there,
From a regulatory standpoint, there is a big difference in going from CN to TSXV/TSX as the listing and reporting requirements are much more stringent on the companies. This is why CN stocks tend to be more speculative, and more volatile as there are few controls in place.
Once you graduate from CN to TSXV it brings along more credibility, and opens up investment from new investors who typically don't tap into CN stocks.
When one graduates from TSXV to the main Index, it has a similar effect on credibility and once again opens up more investors - particularly institutional investors. The stock becomes more well known, and liquidity typically jumps. Depending on the stock, it may also qualify for ETFs and Mutual funds, of which there are more that cover TSX than TSXV stocks. On the flip side, more eyes and institutional investing isn't always a good thing. It can also mean more shorts and higher expectations from the companies. If these expectations aren't met, they can struggle quite significantly.
In my opinion, there is a bigger 'credibility' jump from CN to TSXV just from a pure regulatory standpoint. From the TSXV to TSX is when you make the jump to the big leagues if you will which comes with more potential, but higher expectations.
Mat