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First we'll solve for case a): the small red wooden square block differing exactly one way. We figure out the alternatives for each feature while holding the other features constant.\n\n For different material, keep size, color, and shape constant, we have one difference: small red wooden square vs small red plastic square, yielding 1 different block.\n\n For different size, keep material, color, and shape, we have two differences: small red wooden square vs medium/large red wooden square, yielding 2 different blocks.\n\n For different color, keep material, size, and shape constant, we have four differences: small red wooden square vs small white/blue/yellow/green wooden square, yielding 4 different blocks.\n\n For different shape, keep material, size and color, we have five differences: small red wooden square vs small red wooden triangle/rectangle/hexagon/octagon/circle, yielding 5 different blocks.

Next we add up the numbers of each group of different blocks. So in total, we have 1 + 2 + 4 + 5 = 12 blocks that differ in exactly one way from the small red wooden square block.

To solve for case b): the large blue plastic hexagonal block differing in exactly two ways, we use the same concept but this time for two elements changing, yielding more alternatives for each combination.\n\n Combining material and size, color and shape staying the same, we have 2 differences in sizes and 1 in material, that makes 2*1 = 2 blocks.\n\n Combining material and color, size and shape staying the same, we have 4 differences in colors and 1 in material, which is 4*1 = 4 blocks.\n\n Combining size and color, material and shape staying the same, we have 2*4 = 8 blocks.\n\n For material and shape, size and color staying the same, we have 5*1 = 5 blocks.\n\n For size and shape, material and color staying the same, we have 2*5 = 10 blocks.\n\n For color and shape, material and size the same, we have 4*5 = 20 blocks.

Adding up the numbers of each group of different blocks for this case, we have 2 + 4 + 8 + 5 + 10 + 20 = 49 blocks that differ in exactly two ways from the large blue plastic hexagonal block.