Online marketing uses all the latest technologies (social media, SEO, online ads, email marketing, etc), it is much more interactive and measurable. Classic / offline marketing is mostly based on printing material and the ROI takes more time to be measured, if ever actually measured. Online marketing is much more effective, and cheap, while giving much more space for experimentation and testing.
ROI on traditional marketing is much harder to measure than in online marketing. So to actually measure if the both create the same ROI, is not something easy to say. Most probably, online marketing is much more effective most of the time, since, if done correctly, can be very precise and so measurable that if it does not work marketers can make immediate adjustments.
