说句骨感的，恕我失礼，有无高级会员网站内容区别不大
collocations和origins是简略版，因为collocations是顺带整理出附赠给学习者的罢了，本体的话要另外花钱；至于词源对学习者帮助不大，完整的在ODE。
高级会员特权参考下方：
- iSpeaker - helps you to develop your pronunciation and speaking skills
- iWriter - shows you how to plan, write and review your written work
- My Word Lists - create lists of the words you want to learn and test yourself on them
- Teacher resources - downloadable videos, lesson plans, video walkthroughs and activities for use in class
- UPDATED Oxford Text Checker - check any text against Oxford word lists, and create your own word lists and gap-fill activities