Symptoms does not provide information about what the disease is.but signs provide a little more  information about the disease.symptoms  indicate the presence of disease.For example having headache does not mean that we have a brain tumour therefore it is a symptom 
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Sign of a disease is an objective evidence or the medicinal fact of that disease which is detected by a physician on the other hand,symptom is subjective evidence.
sign can be observed by a doctor/physician/nurse but not by the patient whereas symptoms can be experienced by the patient itself directly.
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