The difference lies in the ratio of Propylene Glycol (PG) to Vegetable Glycerin (VG). A 50/50 vape juice has an equal ratio of PG to VG, offering a balance between throat hit and vapor production. A 70/30 vape juice has a higher VG content, leading to larger vapor clouds and a smoother throat hit, but potentially less flavor intensity and throat hit compared to 50/50.