What is the difference between a "dual aperture camera" and a "dual camera"? As far as I know, a dual aperture camera has two 2 apertures (IR sensor) and 2 cameras.
There is no difference.
Ostensibly, the phrase "dual-aperture camera" inherently implies that a device has two cameras (typically with different focal lengths) pointing in a single direction, and that it takes simultaneous photographs from both cameras and combines them into a single photo, i.e. it is one camera with two apertures, as opposed to two distinct cameras.
In practice, however, the term "dual camera" is almost invariably used to refer to a dual-aperture camera. Thus, there is no difference. It's all just meaningless marketing fluff.
dual apperture means based on the light(luminous intensity) the apperture will switch just like human eyes eg:galaxy s9, if the lux is low,low light situations like night ;it will switch to f1.5 to allow more light to the lens and in bright conditions switch to f2.4 to get vivid,bright photos.if a fixed focus camera,then only narrower area will be captured also miss details in photo so its necessary to switch apperture based on available light. Dual camera is just 2 cameras one main lens and secondary for depth focus,telephoto,macro,tof,ultrawide eg:galaxy note8(12mp(main)+12mp(telephoto for 2x optical zoom a=n background blur),iphone 7plus)
Dual camera is simply one camera on the back so you take normal photos and a front camera to take selfies.
The new Phone cameras are there so you have two distinct cameras, one could have a wider lens and a "telephoto" lens or one camera could be to triangulate the background and add an artificial blur to it, among other possible uses.