Is it not lobbying same to corruption?

Many scholars and practitioners say that lobbying is a strategy to be different and achieve goals. From my friends residing in USA and from my reading, I have come to understand that lobbying is a licensed profession. But is it not lobbying influencing government officials in favour of the lobbyist? If so, is it not a corruptive activity?

As my friends in USA told me, big companies lobby higher government officials even to the extent the lobbied could change a government policy in favour of the lobbyist influencing the parliament. But the lobbied officials get service fee after resigning power or change of government. So, what is the difference between lobbying and corruption?

Corruption is illegal internationally condemned, although a few school of thoughts argue that corruption a means of income distribution in situations where there are big income gaps in societies. But we hear lobbying as a legal profession playing a big role in business and politics. Surprisingly enough, lobbying as a profession is popular in USA which advocates good governance. Good governance is meant government officials serve the society unbiased. Lobbying on the other hand means making someone biased for self-interest.

Corruption, though similar to lobbying, is even more criminal activity as individuals or the corrupters appropriate societies resources (money from tax). It is also the best example of bad governance. Why is then lobbying become a legal business?