Your question is very very vague. May be you have not done any serious learning beyond your text books. "What is the HR structure in current organisations " What a question ! On my God.. When you say current organisations, what do you mean... engineering, IT, manufacturing, marketing, sales, research, agriculture, oil exploration, government, private......... HR Department depends upon the size of the organisation, kind of employees working there, whether it is into manufacturing or just marketing alone..... Structure depends upon the size and need of the organisation. Employee Engagement, again, is a vast topic.... This is not something we can simply list out. Engagement varies from organisational point of you.... just business perspective alone is not enough... what kind of business, volume, turnover, profit, geographical spread and so on.
Please frame your question after thinking clearly about what you want to know ultimately.
Best wishes 13th April 2018 From India