Dassault Mirage 2000
As a successor of the Mirage III Dassault significantly modernised this aircraft. Most differences are internal though, so the old and new Mirage look a lot like each other. Like the Mirage III the Mirage 2000 has low delta wings without canards, and semi-circular air intakes with half-cone shock diffusers inside. The nose gear has two wheels. The vertical stabiliser is somewhat higher than the older generation, and is also a bit pointed: at the front it is higher than at the back.
How to recognise the different versions of the Mirage 2000 will be added later.
Confusion possible with
Dassault Mirage 3/5
The first generation Mirage is obviously the main source for confusion. The old Mirages have a single wheel nose gear, a canopy more flush with the top of the fuselage and a straight top of the vertical stabiliser. The same applies to the derivates like the IAI Nesher/Kfir and Atlas Cheetah.
Dassault Mirage 4000
The Mirage 4000 is essentially a bigger, twin jet version of the Mirage 2000 with small canards at the air intakes. Additionally, it has a true bubble canopy. (photo Michael Teiten/WikiMedia)
Convair F-102 & F-106
Convair also had delta wing fighters, the F-102 Delta Dagger and F-106 Delta Dart. They both have the same basic appearance as the Mirages, but have rectangular air intakes. Additionally, the F-102 has a triangular vertical stabiliser.