Outside of regulatory specifications which vary from jurisdiction to jurisdiction it's quite difficult to provide general umbrellas for types of flight simulators. Over the years and around the world a term that meant something in one context may have come to mean something else in another context, or at a different time. We're going to be using the term "entry level flight simulator" here because it's not widely used as a regulatory term and it will allow us to define a concept based on a cross section of regulations. As with all things in flight simulation the non-regulatory definitions are a bit blurry. This will encompass things which some people would call parts task trainers, and many things people would also insist is a sophisticated flight simulator, both are true.
What they are
Despite being "entry level" they are incredibly useful training aids which simulate an aircraft in a general way with an eye towards being easy to use and economical. They provide a physical/virtual hybrid interface that allows the user to control in various ways a virtual aircraft and fly it around a virtual airspace. At their lowest level they have only limited controls, possibly only touch screens for things other than flight controls, and possibly a very limited out the window (OTW) visual. They will display standard instruments and those instruments behave as expected however dials, switches, and such may only be usable with a touch screen. Not all controls may be present.
What they are not
We can't say all entry level simulators are FAA Basic Aviation Training Devices, because some BATDs are actually quite sophisticated and are only certified as BATDs. Generally because they don't meet certain regulatory specifications to be consider something else. Indeed there are some highly sophisticated flight simulators which have no regulatory certifications at all. This may well be very intentional such as the extensive use of touch screens as to allow greater flexibility of the aircraft represented. We would consider all BATDs to be entry level simulators but not all entry level simulators are BATDs
Generally however most entry level simulators don't have a full compliment of physical switches, lights and instruments, etc. The functionality of what is present is usually generic and they represent a class of aircraft rather than a specific aircraft.
Next read about High fidelity flight simulators