Advil is a brand name for the generic drug ibuprofen. According to Drug Patent Watch [1], the patent for Advil expired in 1984, allowing other pharmaceutical companies to produce and sell generic ibuprofen. The active ingredient in both Advil and generic ibuprofen is the same, which means that they should be equally effective in relieving pain and reducing fever.

However, as The Atlantic [2] reports, there can be differences in the inactive ingredients used in generic drugs that can affect how they are absorbed and metabolized by the body. This can result in slight variations in how effective the drug is for each individual. Additionally, the FDA allows a certain amount of variability in the amount of active ingredient in generic drugs, which can also affect their effectiveness.

Despite these potential differences, a study cited by The Guardian [3] found that there was no significant difference in the effectiveness of branded painkillers like Advil and generic versions of the same drug. The study looked at the effectiveness of ibuprofen and found that both branded and generic versions were equally effective in reducing pain and inflammation.

In conclusion, while there may be slight differences in the inactive ingredients and the amount of active ingredient in generic ibuprofen compared to Advil, they should be equally effective in relieving pain and reducing fever. It is always important to consult with a healthcare professional before taking any medication.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/ADVIL
[2] https://www.theatlantic.com/health/archive/2015/03/generic-drugs-the-same-but-not/388592/
[3] https://www.theguardian.com/science/2016/oct/03/do-branded-painkillers-work-better-than-cheaper-generic-ones-iboprofen-nurofen