fileURL <- "https://raw.githubusercontent.com/jey1987/DATA607/master/Week7_Assignment/books.json"
jsonURL <- getURL(fileURL)

fileURL <- "https://raw.githubusercontent.com/jey1987/DATA607/master/Week7_Assignment/books.xml"
xmlURL <- getURL(fileURL)

fileURL <- "https://raw.githubusercontent.com/jey1987/DATA607/master/Week7_Assignment/books.html"
htmlURL <- getURL(fileURL)

df_JSON <- fromJSON(jsonURL)
df_XML <- xmlToDataFrame(xmlURL)
df_HTML <- readHTMLTable(htmlURL)

df_JSON
## $favourite_books
## $favourite_books[[1]]
## $favourite_books[[1]]$bookname
## [1] "The Lost Symbol"
## 
## $favourite_books[[1]]$Author
## [1] "Dan Brown"
## 
## $favourite_books[[1]]$Genre
## [1] "Fantasy"
## 
## $favourite_books[[1]]$`Language Written`
## [1] "English"
## 
## $favourite_books[[1]]$`Copies Sold`
## [1] "1000000"
## 
## $favourite_books[[1]]$`Number of Reviews`
## [1] "120"
## 
## 
## $favourite_books[[2]]
## $favourite_books[[2]]$bookname
## [1] "2 States"
## 
## $favourite_books[[2]]$Author
## [1] "Chetan Bhagat"
## 
## $favourite_books[[2]]$Genre
## [1] "Love"
## 
## $favourite_books[[2]]$`Language Written`
## [1] "Hindi"
## 
## $favourite_books[[2]]$`Copies Sold`
## [1] "12000"
## 
## $favourite_books[[2]]$`Number of Reviews`
## [1] "90"
## 
## 
## $favourite_books[[3]]
## $favourite_books[[3]]$bookname
## [1] "Thirukkural"
## 
## $favourite_books[[3]]$Author
## [1] "Thiruvalluvar"
## 
## $favourite_books[[3]]$Genre
## [1] "Life Science"
## 
## $favourite_books[[3]]$`Language Written`
## [1] "Tamil"
## 
## $favourite_books[[3]]$`Copies Sold`
## [1] "100000000"
## 
## $favourite_books[[3]]$`Number of Reviews`
## [1] "10000"
df_XML
##                                                                     book_name
## 1          The Lost Symbol\n Dan Brown \n Fantasy \n English \n1000000\n120\n
## 2                     2 States\n Chetan Bhagat \n Love \n Hindi \n12000\n90\n
## 3  Thirukkural\n Thiruvalluvar \n Life Science \n Tamil \n1000000000\n10000\n
df_HTML
## $`NULL`
##   The Lost Symbol     Dan Brown      Fantasy English   1000000   120
## 1        2 States Chetan Bhagat         Love   Hindi     12000    90
## 2     Thirukkural Thiruvalluvar Life Science   Tamil 100000000 10000

The three dataframes are not identical. HTML and JSON are of type List, XML is of format table. The data retrieved is also different.