Dear Rohan,
I believe you have an understanding of the BDC(Batch Data Communication). This is a form of data migration, where a transaction will be recorded & saved as a program and is then executed by playing this program to save data to standard tables/custom tables. For this we will be reading a flat file containing the data to run the transaction and supply this data to a standard structure BDCDATA. This is the method that you will be using with the second option of LSMW.
Your question was about the first option Standard Batch/Direct Input.
Standard Batch Input - This uses the classical BDC approach that I had explained above. But here there will not be any sort of recording and converting that to a program. Similarly the data from the flat file is not used to populate the structure BDCDATA. Instead the user had to place the data into predefined structures. This process is slower. Please refer the following link for this:
Creating a LSMW using Standard Batch or Direct Input Recording - ABAP Development - SCN Wiki
Standard Direct Input - This method will directly load the data into standard tables using some standard function modules.This is a faster method, but the error log returned is not that much informative.
Thanks & Regards,
Abijith