If you are considering the Ravens a continuation of the Browns' franchise, fine, but then the current Browns should be considered to go back to 1999.
If you consider the current Browns to be a continuation of the Browns' franchise because they kept the same name, then the Ravens should be considered a new team as of 1996. It really doesn't make sense to say both teams date back to 1946.
This is an all-too-common misconception, concerning the Ravens being a continuation of the browns franchise. The Ravens are, in fact, 100% an expansion franchise, founded in 1996. The misconception comes from the fact that when Modell was granted an expansion team in Baltimore and left Cleveland, he was allowed by the league to take all Browns personnel in his employ with him, so people (and way, way too many people who get paid to know this stuff, NFL Network for example) naturally thought it was the Browns relocated. Nope. 100% expansion, as the league office has clarified. Here's an easy way to remember it: Earl Campbell did in fact play for the Tennessee Titans (before the franchise relocated and changed its name); Jim Brown and Otto Graham never played for the Baltimore Ravens. Despite the fact that almost all of the 1996 Ravens roster had played for the Browns the previous system, they are two separate franchises, founded respectively in 1946 and 1996.
If you are considering the Ravens a continuation of the Browns' franchise, fine, but then the current Browns should be considered to go back to 1999.
If you consider the current Browns to be a continuation of the Browns' franchise because they kept the same name, then the Ravens should be considered a new team as of 1996. It really doesn't make sense to say both teams date back to 1946.