e voting and postal ballot are different things. but postal ballot can be done in two ways i.e through post or through electronic mode
however if we do postal ballot through electronic mode it seems like e voting , but the major difference between the two is time period .In e voting time period is 7 days whereas in postal ballot time period is 30 days
and moreover companies having member more than 200+ ( but less than )have to pass some resolution only through postal ballot
companies having member more than 1000 have to provide e voting facility and may pass resolution as provided in rule 22 of companies administration rules through postal ballot (e voting is also allowed )