Galaxy S10 E: A dual-lens system, with one likely for regular photos, and the other for zoomed shots. Single selfie camera.
Galaxy S10: A triple-lens system, with one likely for regular photos, the other for zoomed shots, and another for ultra-wide angle shots. Single selfie camera.
Galaxy S10 Plus: A triple-lens system, with one likely for regular photos, the other for zoomed shots, and another for ultra-wide angle shots. Dual-lens selfie camera, with one for normal selfies and the other for ultra-wide angle selfies.
Galaxy S10 X: A four-lens camera system, with one likely for regular photos, the other for zoomed shots, and another for ultra-wide-angle shots. (It's unclear what the fourth lens could be used for. It's pure speculation, but the fourth lens could be purely complimentary for portrait mode enhancements.) Dual-lens selfie camera, with one for normal selfies and the other for ultra-wide angle selfies.