This looks like a good deep end to jump into:

747-400: Winglets above the wing only
A320-series: Winglets above & below wing
(not that you'd ever confuse one with the other )

727: 3 engines in back, #2 engine (in tail) offset air intake
L-1011: engine in tail with offset intake, other 2 engines under wings
DC-10/MD-11: Only aircraft with straight-thru tail engines

DC-9: 2 engines only in back (also BAC-111, F-28, others)
MD-80&90 series: Like DC-9, tail ends in tab, instead of point
B-717: originally part of MD-90 series (MD-98??)

707: narrow tube, 4 engines under wings
DC-8: like above, with 2 vents in nose visible when viewed head-on
B-52: 8 engines (in pairs) under wings

BAE-146: 4 engines under high wing (short & stubby)