A filter is typically made of paper and is used to separate particles of different sizes. A sieve, on the other hand, is made of metal or plastic and is used to separate particles of different shapes.

The micron rating of a filter refers to the size of the particles that it can capture. A filter with a higher micron rating can capture larger particles than a filter with a lower micron rating.

The mesh size of a sieve refers to the size of the openings in the sieve. A sieve with a larger mesh size has larger openings than a sieve with a smaller mesh size.

The right lab filter or sieve for your application will depend on the size of the particles you are trying to separate. If you are unsure of the size of the particles, it is always best to start with a filter or sieve with a smaller micron rating or mesh size. You can then increase the size as needed.