What is the difference between accuracy and precision?
The difference is:
The closeness of an experimental result to the true value, i.e you determine the concentration of something using a method to see if you get the same concentration that was specified to that specific compound that was given to you prior to the experiment.
The closeness in values of replicate experiments done, i.e you do an experiment multiple times and compare for example the concentration values you obtained in the experiment. If they close to each other there is a high degree of precision.
The two can be distinguished using this analogy:
Image from: http://www.antarcticglaciers.org/glacial-geology/dating-glacial-sediments-2/precision-and-accuracy-glacial-geology/
Hope I helped 🙂