Total impact is dramatically less. I mean, stealing a candy bar is wrong, and it has a real, measurable impact; stealing a car is also wrong, and has a real, measurable impact. but most people (and the law, at least in my jurisdiction) would make a distinction between the two crimes; one results in a 'slap on the wrist' while the other usually involves jail time and a felony record that makes it quite difficult for the perpetrator to get a legitimate job.
For that matter, there's another difference. In both sports and finance, most of the money is in the surrounding ecosystem, not in the traders or athletes themselves. The difference here is that if one athlete wins instead of another because of doping, this doesn't really effect the ecosystem all that much. Okay, so reebok gets the extra shoe sales rather than nike, but you are going to probably move about the same number of units at about the same price with about the same labour input. One athlete winning over another has nothing to do with the actual efficacy of the reebok or nike design or manufacturing operations. The wronged party is mostly the athlete that doesn't dope.
But the stock market is different. The stock market is how nearly all the corporations we work for and buy stuff from are owned. Stock prices directly effect things like how much labour is put towards food production vs. car production. There are real consequences to miss-allocated capital that are much larger than what brand of overpriced shoes is popular this week. Potentially, for instance, miss-pricing food commodities could cause starvation.