The blue dot that appears after the first block is selected is the base point of the block, and the block can be moved by dragging the base point; The point without blue in the second block should be that the base point was not selected manually when defining the block, and the default base point of cad is (0,0,0) (or the base point is selected as the far point when defining the block). In this case, you can find the base point by zooming the window.
If you want to change the base point, you can blast the block and redefine it. If it is inconvenient, you can use the Block Editor to change the base point.