What is the difference between Biblical and Modern Hebrew?
Biblical and Modern Hebrew are extremely similar – and in many cases identical. There are many words which have made it into the Modern Hebrew lexicon which you naturally will not find in the Hebrew Bible, and there are some very minor differences in grammar and vocabulary. These two "versions" of Hebrew overlap probably 95% of the time or more.
So whether you want to learn Modern Hebrew or Biblical Hebrew – or both – you can count on the fact that learning one will help you know the other.