|(Pair of Zebras @ Toronto Zoo)|
Have you ever asked yourself what differentiates a Zebra vs. Horse? They are both part of the Family "Equus" and some sources say the name the word "Zebra" comes from Portuguese meaning "Wild Horse" or "Wild Donkey". However, as much as a Zebra looks likes 'White' Horse with 'Black' stripes, turns out they are physiologically quite different. Zebras are said to be very hard to tame, have solid (aka "meaty") tails and ultimately Zebras are only native to Africa continent. For more info see here and here.
So for your apps, you need to take a look at how different it *would* or *could* run on Tablet vs. Phone. Can a single code-base run with enough detection/adaptation code to adjust properly on both formats? Would future enhancements or changes to one platform but not the other cause issues?
For example, look at my friends at NitroDesk, who offer a 'popular' (to the tune of 2 million users) very "security-focused" 3rd-party Email-App Vendor. Their Android offerings have both a Phone (aka "smartphone") and Tablet (aka "HD") version.
|TouchDown email for Android SuperPhones|
|TouchDown email for Android Tablet|
For us @ SAP, for the current mobile app I am working the answer was 'NO'. So the group I am working with has chosen to create separate a Tablet and Phone optimized with different IxD. (Note: The plan is actually for eventually 4x releases, iPad, iPhone, Android Superphone & Android Tablet.)
Yes you can 'code' some of the logic into the app to auto-detect the screen size, density and layout, but especially for Android with the "Fragmentation" (not to be confused with a code android.app.fragment... I will have a posting on this topic soon...keep an eye out for it...), I don't believe this is going to be always 100% reliable.
My current advice is to design and offer 2x different apps and guide the end-user to pick the optimal version. Ultimately I'd rather have 2x great apps posted vs. 1x mediocre one.
A Zebra is in fact not just a White Horse with Black stripes.
Just like a Tablet is not just a bigger Phone, and therefore we shouldn't treat it as such.
Hope that helps...
p.s. Yes, the opposite is also true. Can you "pigeon hole" users with 2x different apps? With both a Tablet and Phone optimized apps, what about Phablet users? My suggestion is to make Tablet and Phone optimized apps, but not restrict them via the app store (ie. Android Manifest file, etc). This way for users of a device that is a hybrid they can test out *both* apps and find which works best for them.