An old adage, when I was backpacking years ago, was the a tourist had lots of money but very little time; a traveller had lots of time but very little money.
Under that scenario, a tourist may have a bad influence as they just breeze in, spend lots of money and leave, potentially driving up prices because the salesmen / restaurant owners etc can sell to the tourists at a higher price, causing resentment to the locals. Against that, a tourist (usually) injects more money in to the local economy, perhaps benefitting society as a whole. This depends on where they eat, sleep etc. Staying in top end hotels that are owned by foreign companies doesn't do much for a poorer country's economy, whereas staying in local places and eating in locally owned restaruants will do.
A traveller may stick around for a while, get to know people and the culture, shop in local markets, stay & eat in places likely run by locals etc, but not actually put much into the community.
And to contradict the previous response...I live in London and have been "a tourist" in my own city. I went out armed with a camera one day, went to a selection of the touristy places, went on guided tours and did what tourists do best - visited places & SAW my city, rather than just walk past places that I generally take for granted because they're always there.