It is called ‘Classical Orthography’, but in fact it is a different language standard. The two forms of Belarusian stemmed from a Soviet language reform that has (arguably) brought Belarusian closer to Russian (on the other hand, academic Belarusian is, arguably, closer to Polish).

Official Belarusian is taught at schools, but those who use Belarusian every day often prefer Classical one. Classical is rather widespread in the Internet. Laws accompanying a new (minor) reform of the official Belarusian in 2007 also have in fact banned the use Classical Belarusian in press.

Apart from merely orthographical differences (сьнег/śnieh vh снег/snieh; робісся/robiśsia vs робішся/robišsia), there are lexical and grammatical ones.

A big problem is the transcription of loanwords. They aren’t simply written differenlty, they are pronounced differently. In Official Belarusian they are (somewhat inconsistently) borrowed from Russian or using similar transcription system, whilst in Classical they are borrowed from West-European languages directly: метр/mietr vs мэтр/metr for meter, опера/opiera vs опэра/opera, сымбаль/symbal vs сімвал/simvał, Атэны/Athens vs Афіны/Afiny.

There are also some grammatical forms acceptable in Classical Belarusian but considered dialectal in official (synthetic future tense: рабіцьму/rabićmu vs. буду рабіць/budu rabić), and different tendencies towards forming some forms (Gen. pl. of мова can be моў or моваў; classical prefers the latter whilst official the former).

There are also some words words considered Russisms/Polonisms in one variant and widespread in the other (працэнт/pracent vs адсотак/adsotak; цячэнне/ciačeńnie vs плынь/plyń).

Automatic conversion is possible, but there is no aviable open-source software to do this. The only one I know is “Litara”, a plugin for MS Word 2000 (http://pravapis.tut.by/), which is closed-source and is unlikely to be ported to new versions of Word because of Microsoft’s new policy (now it’s necessary to obtain permission from MS).

Wikipedia has 2 versions (be and be-x-old).

I feel like adding a bit of Belarusian sentences. Could you please add it?

I’ll add sentences in Official Belarusian, so I suggest marking Belarusian with the current flag of Belarus.

Those who use Classical Belarusian don’t like that flag anyway. :)