There are several "main" differences, that are important, depending on what context you are interested in them for.
PowerPC processors are primarily manufactured by IBM and Freescale. Pentium processors are manufactured by Intel.
PowerPC processors can operate in both little-endian and big-endian modes. Pentium processors (and compatibles) are little-endian only.
PowerPC processors are used in some servers, game consoles, and in embedded kiosks. They were also used in Macs before 2005. Pentium (and compatible) processors are used in most desktop computers, the original Xbox, servers, and some embedded kiosks.
The basic diffreence is that in a mobile processor, they build it so that it uses as little power as possible, so that your battery lasts as long as possible. There are many ramifications to this, but that's the motivation.
The difference is that Core Duo processors have to "engines" instead of one. With other words, Core Duo means 2 Intel processors in the same time working!
On the Pentium II, the L2 cache is integrated into the processor packaging, rather than on the motherboard. This allows the L2 to be accessed much faster, and improving overall performance.
pentium 4 more faster
There is no "Pentium R" processor. Knowing this, the biggest difference is that the Pentium III exists and the other does not.
PowerPC processors can only be used in computers or peripherals that were originally designed to run them. Some computers that have PowerPC or PowerPC-based processors include:* Macs made between 1994 and 2005 * The Pegasos and Pegasos II (a desktop computer designed for operating system developers) * the EFIKA (a motherboard for embedded systems) * The GameCube uses a custom PowerPC-compatible CPU * The Wii uses a custom PowerPC-compatile CPU based on the one in the GameCube * The Xbox 360 uses a triple-core PowerPC-based CPU * The PS3 uses the Cell processor, which is based upon and mostly compatible with PowerPC processors. * The AmigaOne, a computer designed to be the successor to the 68k-based Amigas.
Celerons have a smaller amount of L2 cache.
Pentium 4 is a family of Intel processors with one core based on the NetBurst architecture, but some types support Hyper-Threading technology that exposes an additional, "virtual" core to the OS. Core 2 Quad is another kind of Intel processors with four cores, based on the Intel Core architecture.
A single core processor is just that... one processing core. A dual core processor is actually two processing cores on one chip. It is like having two processors in your system, but it is faster than two individual processors.
The Intel Pentium line encompasses many processors of many different architectures ranging from the original Pentium Processor of 1994 up to the Core 2 Duo based Pentium simply called the "Pentium". The Intel Pentium used to be Intel's flagship processor. Recently this position has been taken by the Core 2 Duo and Core i7. The Pentium now is reduced to a budget processor that offers lower performance but also lower cost.
The clock speed, architectural design, and socket types are different between these three types of processor. Making the transition to dual pipeline architecture and integrated cache happened during this as well. In essence, these processors are basically nothing alike. They look different, behave different, perform different, and handle internal functions differently.
The Pentium Dual Core has a smaller L2 cache than a Core 2 Duo. It essentially fills the same role as the older Celeron processors; a cost-reduced version of a more powerful chip.