Velocity is a more widely used term, usable for all moving objects and waves, while wavelength is of course only usable for waves.
Wavelength is the minimal distance between two points of a wave with the same phase. Take for example a sinusoidal wave: the wavelength will be the difference between two maxima or two minima.
The velocity of a wave is used more often in wave packets: a composition of waves. These can travel with a different speed than the individual sinusoidal waves. So the velocity of a wave packet will be the speed that the center of the wave packet will travel with.
In your equations, the d will also usually represent total distance, while lambda is usually a very small distance and remains fixed for a particular sinus wave. But take for example a wave which has travelled N times its wavelength lambda, and did that in a time t, then t will be N times its period. And since the period = 1/f we have: v=d/t = Nlambda/Nperiod=f*lambda.
The properties and formulas depend on what kind of waves you are talking about so I hope this is not too confusing.