LEA and MOV are doing different things. LEA is just calculating the effective address, but MOV calculates the address then retrieves the value stored at that address.
e.g. If base + (index * scale) + offset = 42, and the value at address 42 is 3, then:
LEA rax, [base + index * scale + offset] will set rax = 42
MOV rax, [base + index * scale + offset] will set rax = 3
e.g. If base + (index * scale) + offset = 42, and the value at address 42 is 3, then:
LEA rax, [base + index * scale + offset] will set rax = 42
MOV rax, [base + index * scale + offset] will set rax = 3