When I saw this difference first time on my newly bought laptop almost three years ago I did not know the difference between these two configurations as I really enjoyed my new computer very much and nothing else matters. Soon the learning of this came and slowly I understood much better.
First of all 32-bit Windows Operating System is able to recognise and work with approximately 3GB of RAM and sometimes even less. It means that no matter how much you put RAM into your computer your Windows OS it will be able to read just these 3GB. If you put 4, 6 or 8GB the situation will be always the same. To make your RAM readable you must install 64-bit OS. I remember when I put into a computer's client with 32-bit OS 4GB of RAM and to my disappointment only 3.2 GB had been recognised. What a shame to learn about it after fact. It was hard learning lesson.
Secondly, more and more software developers released more and more hungry for computer resources applications and to work without any significant issue you need bigger and bigger amount of RAM. 64-bit operating systems and application can do these jobs really smoothly. To be able to work with 64-bit applications you need 64-bit operating system. If you try to do this with your 32-bit OS edition sooner or later on the screen will appear a message about the installation mistake.
The last main consequence between 32 and 64-bit Windows editions is the fact that if a processor and RAM of a computer are not strong enough you have no chance to install any 64-bit editions. The hardware of a computer can show many mistakes during the installation process and you can spend a long time trying to figure out why your 64-bit OS cannot be installed in any possible configuration.
When you buy a new laptop or desktop nowadays most of these computers have 64-bit OS inside. Remember that this issue applies to machines released mainly 2 or 3 years ago.
During more than year of practical experience with client computers I had a few cases when the only radical solution to help clients and their computers was re-installations of their operating systems. It was happening in cases when the computer was really slow and the whole usage of a machine was really painful and problematic experience. After adding an extra RAM memory and re-installation the OS computers significantly speeded up and everybody was happy.
Unfortunately, in 3 out of 20 cases this operation was only partially successful and not because computers stopped working completely but because after a few months of relatively good performance problems came back or something else happened which disabled the computer completely from any performance. At the beginning I was really disappointed with these cases and wanted to repeat the same operation for a while but after a few weeks of thinking about it I realised that an each computer has its lifetime and it is really not worth revitalise something what can stop working in next day from an unknown reason.
From a gathered experience I know that it is worth to talk to a client about the options for future computer usage as most of computers today are relatively not expensive and the cost of repairing a problematic machine can be much higher than a value of a new computer which after a relatively short tuning process will work for about 2-3 years without any bigger issues. This decision must be made what is much worth - repairing a ageing computer which has not warranty or investing in a new computer which is more up to day and a warranty from manufacturer.
What would you do?
Last three days I was dealing with an old computer of a long-term client which has a quite impressive collection of music inside his computer and after running a few previous backups we decided that his computer will be replaced by something newer and faster. To find a newer computer was not a bigger issue but much bigger challenge was to backup a data from his old machine and transfer this data to a new environment. Music files were everywhere and in sometimes incompatible formats which did not give any chance to play them in one music player. From the surface it looks like a relatively short job but unfortunately the old hard drive refused to work for longer and the only source of data was imperfect backups created by Acronis. It took a few hours to make a certain order with this mess and therefore I love this job.