[Anumana (inference)] Inference is preceded by perception and is of three types- past, present and future. For example: fire is inferred from the coming smoke and sexual intercourse from pregnancy - these are inferences drawn from the present and the past respectively.
By looking at a seed, one can infer about the species or genus of the plant or tree and the kind of fruits it would bear. This inference is drawn on the basis of repeated, empirical observation of the plant’s (or tree’s) lifecycle and is an example of inferring (or predicting) the future.
[Yukti (reasoning)] Water, ploughed piece of land, seeds and the season in which particular seeds are sown, when combined together, result in a crop. Similarly, combination of six factors (pancha mahabhuta and atman) is responsible for formation of a fetus in the uterus.
Fire is produced by lower-fire-drill, upper-fire drill and the act of drilling or churning done by a person. In a similar manner, the treatment of disease is possible by applying the fourfold therapeutics measures (The vaidya, medicines, paramedical staff, and the patient).
The intellect perceives things by combination of multiple factors, valid for past, present and future is termed as yukti (reasoning). This is helpful in fulfilling three basic objects of human life (dharma, i.e. duties, wealth, desire).