You guys may have 10 times their population, but Djibouti has a $2.09 billion economy!
The per capita of Djibouti is 2x that of Somalia so they have more money to spend on weaponry. lets keep ethnic emotions out of this discussion, when it comes to war no Djiboutan citizen would fight for Somalia.
Djibouti has 2 Hind mil-mi 24 helicopters which is can use to fight somali army from the air and it also has transport aircrafts to fly over somali territory instead of fighting through land.
Size of economy, and even size of armed forces does not determine power.
Djibouti has a small and well equiped force that is more disciplined then any other somali force, so they will win in most situations.
As their size is too small, any enemy that can throw manpower at them will defeat them.
No look at the example of Saudia.
On paper they are a super power, rivaling Isreal and Turkey and Egypt in terms of power.
In realty they lack training , dicipline and are worthless.
To be totally honest , hypothetically if Jordan was allowed to conquer and take over Saudia and create a new Hashimte kingdom.
They will overrun and own all Saudi forces in a matter of weeks.
Even though what weapons the saudis have are a generation ahead of jordan, and they have 4 times as many personel in the armed forces.
The Same with the UAE, the UAE does not fear its army so they allowed them to train to a decent standard, and they armed with the most modern weapons available. UAE's 40,000 army will easily defeat Saudia's 250,000.
The Same with Oman's 20,000 army versus Saudi'as 250,000, they are seperated by the rubc al khali impassable desert so
lets say we magically transport the entire saudi armed forces with all their bases and logistical support and drop them on omans border.
my money is on the small 20,000 man omani army winning.