There may be small difference in physical properties such as melting or boiling point due to different strengths of intermolecular bonding. Their chemistry is likely to be identical.
Positional isomers are also usually similar.
There are slight physical differences, but the chemical properties are usually very similar. However, occasionally, positional isomers can have quite different properties e.g. oxidation of alcohols. Functional group isomers are likely to be both physically and chemically dissimilar. Geometric isomers of one another usually have very similar physical and chemical properties. But, it is important to realise that this can have significant effects in a living system.