Both reflow and wave solder are used to attach components to the board, but they have different applications.
Reflow is typically used to solder surface mount devices. The process steps required include:
screen printing a solder paste to the PCB
Placing components onto the PCB
Running the PCB with the mounted components through a reflow oven (this causes the solder to liquefy and then upon cooling create the solder joint and the mechanical adhesion of the component to the PCB)
Wave solder is typically used to solder through-hole components to a PCB. The steps to perform wave soldering vary from reflow soldering, as well as the equipment necessary. The typical process is:
Insert components into the PCB
Convey populated PCBs into the Wave Solder machine
Inside the Wave solder machine there is a pot of molten solder that the PCB gets conveyed across which allows the component leads to get soldered.
Obviously, this is an extremely high level description of both processes. There are many factors involved to successfully solder components to PCB, including whether you are doing lead-free soldering or not; what type of flux you are using etc.
Are you trying to implement a specific process, or are you considering the soldering processes from a product design perspective?
Let me know,