Place and manner of articulation:
In the International Phonetic Alphabet, both retroflex and lateral sounds are classified under “approximants” (a manner of articulation), they are defined as (most cases) occurring in the alveolar ridge (**the retroflex may occur in the hard palate, see here) (place of articulation). The lateral consonant may be produced in other regions of your mouth as well, see here (and see below), but for our purposes we will classify it as a consonant occurring in the alveolar ridge.
How are they produced?
In the production of these sounds the tongue produces partial closure in the mouth, but air is escaping. The air quality is not turbulent, so these sounds are not fricatives. They “approximate” at a closure, air is escaping, and they both have vowel-like qualities to them.
Together /r/ and /l/ sounds are also called liquids sounds because of their resonance and vowel-like quality.
English Phonetics at UPRM 