I don't know if it is the composition that is causing this difference, because the main companies are in both indices.
I think this distortion is caused because your chart (EWZ) is in Dollar, while Ibovespa is in Real (Brazilian currency). So, if you dollarize Ibovespa chart (Ibovespa/Dollar) and compare with EWZ, you will see that they are very similar.
In other words, the Ibovespa index has inflation that distorts a little the chart in a medium/long term.
Have a look at this chart: BVSP/USDBRL
Ps: The right name for the Brazilian index is "ibovespa" (with "i"). But Tradingview put "bovespa"... I don't why... "Bovespa" is the name of the exchange. : )