To me...the outdoor filter is mainly a pre-filter that removes solid particles and other harmful materials so that it is safe for showers and washing.
Most importantly does not stain while doing laundry. And also this water will be stored in our tanks. The cleanliness of tank should be also considered when installing an outdoor filter.

Meanwhile, indoor filters must be safe for drinking or washing veges & fruits..especially for the kids.

Outdoor filters are usually 5-10 microns which I also think is very sufficient and also that any finer filtration will just shorten the life span of the filter since the water quality in Malaysia varies especially during rationing.

Maintenance is also crucial for water quality & life span of the product. For those lazy/busy folks...outdoor filters also comes with an option for automated flushing..but manual backwash still has to be done at least once a month.
This also helps promote the life-span of your indoor filter.

As for indoor filter..I would recommend one that has a pre-filter built together especially for those condo users that can't install an outdoor filter.
This pre-filter is basically to filter like an outdoor filter (5 microns) solely to maximize the water quality and lifespan of the main filter. This pre-filter can be washed or changed at very minimal cost (RM3-5).

And also for indoor filter..one should also consider on the design..
ie: Under counter type with a single filter tap on top of the counter or sink or built-in filter output with your sink tap
or
Desktop type with single output
or
Desktop water dispenser.

Just my 2 sens

Cheers

To those looking for simple drinking filter can consider Coway Genie P-07IU. Can look at the specs here

I am using it for my own house and its performing well...and the maintenance is cheap..for me it lasted around 1 year before needing to replace the cartridge
The retail price is RM490. Worth considering...

Can also be converted to be installed under the counter!

My showroom also has it...if you wana know my offer..can PM me

Thanks