This article gives the difference between hadoop and big data.
I personally found many students have confusion between hadoop and big data. Actually both are different entity. In one sentense I would say “big data is the problem” and “Hadoop is framework which provide the solution to resolve big data problem.”
When you go for big data interview , Interviewer may ask you the questions based on hadoop,cloud plateform.
We can put huge amount of data on cloud plateform like AWS,Google cloud and we can use hadoop framework to process those data.
I can see there are many opening now a days for hadoop development and its really good to have knowledge on cloud along with hadoop which makes you one step ahead to your competitors.
there are many online hadoop tutorial available which will give you understanding for hadoop ecosystem.