Great v good books

it is the season of literary prizes; more specifically, the Nobel and the Booker. The Times has also published this week the titles of the first batch of its ' 60 best books of the past 60 years' survey. Among the top 20 are Harry Potter, Doctor Zhivago and The Time Traveller's Wife, and this set me thinking: what is the difference between a great book and a good book? There are books which have kept me riveted (Sandra Brown's thrillers spring to mind) but which I know are not great, and books which I recognise as being great literature (eg some Trollope (Anthony), much of Iris Murdoch), but which may not have been quite so un-put-downable. There is certainly room for both - in fact, both kinds are essential - and yet I find it hard to explain what it is that makes me feel that a book is great rather than just good. What does anyone else think? And what are, say, your top five books (published in the last 60 years) for whatever reason? Mine, for what it's worth, would be Brothers (Bernice Rubens), A Fine Balance (Rohanton Mistry), The Secret history (Donna Tartt), The Diary of Jane Somers (Doris Lessing) and The Tin Can Tree (Anne Tyler). The Tin Can Tree is a compromise as I couldn't quite make up my mind, but the delicacy of the writing in this quite slight novel, which describes beautifully a family's reactions to the death of a little girl, and takes place over just a few days, shows a mastery which I find quite breathtaking.