Radio is an effective advertising medium because it's 100% audio-based. The advertiser's message has to be a combination of copy, sound design and voice over. Additionally, a radio ad is cost-efficient, targeted, easy to track, and extremely effective if done properly. Regular playing of commercials plays an impactful branding in market . 
Television is the whole package as an advertising medium. It's visual like print advertising, and auditory like radio at the same time. While a newspaper or magazine must be picked up and its pages turned for an ad to be seen, television reaches out to its audience whether they want it to or not. A brand's presence on TV can lend credibility. It exposes that brand to a much larger audience initially than online advertising.