Slots do have wide variations in their odds and its very difficult to determine it. Some slots have regular wins but its hard to achieve a jackpot while some keeps on making you lose and some people claim they had won a huge jackpot there. So, it's not the same for everyone as it also depends on luck.
When I play slots, I keep on changing the machines till I find the one I love. Last year, I was into slots for months and I tried about a hundred slots before being stuck to a single one called Jungle Safari or something. The beauty of it were it had regular bonus rolls as win and those bonus roll gave more money. I lasted long on that slot.