a1 = [
    [
        [91,15,25], [4,14,25]
    ],
    [
        [91,115,215], [41,154,148]
    ]
]


b1 = [
    [
        [41,4,14], [3,5,14]
    ],
    [
        [266,41,73], [366,13,91]
    ]
]


x = \
[
    {
        a__
           for a_ in a
           for a__ in a_
    }
    & 
    {
        b__
            for b_ in b
            for b__ in b_
    }
    for (a, b) in zip(a1, b1)
]

print(x)