Preventing interference between over-the-air channels in the same area is accomplished by skipping at least one channel between two analog stations' frequency allocations. (Where channel numbers are sequential, frequencies are not contiguous, such as channel 6 to 7 skip from VHF low to high band, and channel 13 to 14 jump to UHF.)
On cable TV, it is possible to use adjacent channels only because they are all at the same power, something which could only be done over the air if the two stations were transmitted at the same power and height from the same location. For digital TV, selectivity is inherently better, therefore channels adjacent (either to analog or digital stations) can be used even in the same area.