Show clock shows where the routers clock is pulling time. By default it is the hardware calendar. This is why the output looks the same to you. If you set up the router for NTP for example it would not look the same. "show clock detail" will show where the router's clock is pulled from.
Default
7200-1#sh clock det
*19:17:12.731 UTC Mon Jan 13 2003
Time source is hardware calendar
with NTP
7200-1#sh clock det
19:12:39.715 UTC Mon Jan 13 2003
Time source is NTP
Hope this helps you,
Don