ASICs vs FPGA

FPGA	ASIC
Definition A semiconductor device containing programmable logic components called "logic blocks", and programmable interconnects. Logic blocks can be programmed to perform the function of basic logic gates such as AND, and XOR, or more complex combinational functions such as decoders or mathematical functions.	Definition An integrated circuit designed for a particular use, rather than intended for general-purpose use. Processors, RAM, ROM, etc are examples of ASICs.
Speed Less speed.	Speed ASIC rules out FPGA in terms of speed. As ASIC are designed for a specific application they can be optimized to maximum, hence we can have high speed in ASIC designs. ASIC can have hight speed clocks.
Cost FPGAs are cost effective for small applications.	Cost For complex and large volume designs (like 32-bit processors) ASIC products are cheaper.
Size/Area FPGA contains lots of LUTs, and routing channels which are connected via bit streams(program). As they are made for general purpose and because of re-usability. They are in-general larger designs than corresponding ASIC design.	Size/Area  Optimised , so smaller
Power FPGA designs consume more power than ASIC designs. The unwanted circuitry results in wastage of power. FPGA wont allow us to have better power optimization.	Power When it comes to ASIC designs we can optimize them to the fullest.
Time to Market FPGA designs will take less time, as the design cycle is small when compared to that of ASIC designs.	Time to Market ASIC designs will take more time
Type of Design It is not possible to design mixed signal designs or only analog designs using FPGA chips.	Type of Design ASIC can have mixed-signal designs, or only analog designs
Customization FPGA has less customization.	Customization ASIC has the upper hand when comes to the customization. The device can be fully customized as ASICs will be designed according to a given specification.
Prototyping Because of re-usability of FPGAs, they are used as ASIC prototypes. ASIC design HDL code is first dumped onto a FPGA and tested for accurate results. Once the design is error free then it is taken for further steps. Its clear that FPGA may be needed for designing an ASIC.
Non Recurring Engineering/Expenses NRE refers to the one-time cost of researching, designing, and testing a new product. No such thing is associated with FPGA. Hence FPGA designs are cost effective.	Non Recurring Engineering/Expenses NRE  is generally associated with ASICs.
Design Cycle  Due to software that handles much of the routing, placement, and timing, FPGA designs have smaller design cycle than ASICs.	Design Cycle  ASICs have larger design cycle.
More Predictable Project Cycle Due to elimination of potential re-spins, wafer capacities, etc. FPGA designs have better project cycle.
Tools Tools which are used for FPGA designs are relatively cheaper than ASIC designs.
Re-Usability A single FPGA can be used for various applications, by simply reprogramming it (dumping new HDL code). By definition ASIC are application specific cannot be reused.