Welcome to Tom's Forum!
I assume you're asking 'What's the difference between Pentium D and Core 2 Duo?'
First it depends on the specific CPU, but here's a generalized comparison.
The advantages to the Core 2 Duo:
FSB Speed 1066MHz vs 533MHz
Lithography 65 nm vs 90nm
Lower TDP
Intel® Virtualization Technology (VT-x)
Enhanced Intel SpeedStep® Technology
Thermal Monitoring Technologies
Pentium D -
http://en.wikipedia.org/wiki/List_of_Intel_Pentium_D_microprocessors
Dual-core microprocessor
No Hyper-Threading
800(4×200) MHz front side bus
LGA 775 (Socket T)
Smithfield – 90 nm process technology (2.66–3.2 GHz)
Introduced May 26, 2005
2.66–3.2 GHz (model numbers 805–840)
Number of Transistors 230 million
1 MB × 2 (non-shared, 2 MB total) L2 cache
Cache coherency between cores requires communication over the FSB
Performance increase of 60% over similarly clocked Prescott
2.66 GHz (533 MHz FSB) Pentium D 805 introduced December 2005
Intel Core 2 -
http://en.wikipedia.org/wiki/Intel_Core_2
Conroe – 65 nm process technology
Desktop CPU (SMP support restricted to 2 CPUs)
Two cores on one die
Introduced July 27, 2006
SSSE3 SIMD instructions
Number of Transistors: 291 Million
64 KB of L1 cache per core (32+32 KB 8-way)
Intel VT-x, multiple OS support
TXT, enhanced security hardware extensions
Execute Disable Bit
EIST (Enhanced Intel SpeedStep Technology)
iAMT2 (Intel Active Management Technology), remotely manage computers
LGA 775