One way of doing it would be to oxidise both under distillation such that you get a carboxylic acid in the case of the oxidation of the aldehyde, and in a separate apparatus you would get an aldehyde or ketone depending on the class of alcohol. With each distillate, you could react them separately with sodium carbonate or sodium hydrogen carbonate, you would observe effervescence with the carboxylic acid as CO2 is released. You wouldn't observe anything from the alcohol distillate; the aldehyde. Between distillations, make sure to keep track of which is which. There is another way with two oxidations under distillation, but that would only work in the case of a primary alcohol because you wouldn't distinguish between them upon the second oxidation since the ketone would be resistant to oxidation in these conditions, as would the carboxylic acid.