For example if you would need some sort of bytewise memory comparison block in your application (generated by compiler, skipping details), this is how it might look like on x86
repe cmpsb /* repeat while equal compare string bytewise */
while on ARM shortest form might look like (without error checking etc.)
top:
ldrb r2, [r0, #1]! /* load a byte from address in r0 into r2, increment r0 after */
ldrb r3, [r1, #1]! /* load a byte from address in r1 into r3, increment r1 after */
subs r2, r3, r2 /* subtract r2 from r3 and put result into r2 */
beq top /* branch(/jump) if result is zero */
which should give you a hint on how RISC and CISC instruction sets differ in complexity.