These processes are very similar, but coastal erosion is more wide term, then the abrasion. In general, abrasion is mechanical scraping of a rock surface by friction between rocks and moving particles during their transport by wind, glacier, waves, gravity, running water or erosion. Including all that relates to abrasion, coastal erosion have some chemical factor like a solution and corrosion and physical factor, like a hydraulic action.

Abrasion is a physical action of the coastal erosion (with chemical and biological actions also).

Sergio, you are right, abrasion is a physical action of the coastal erosion, but chemical and biological weathering are related to actions of coastal erosion, not to abrasion. Coastal erosion is complex of actions and abrasion only one of this action.

I totally agree

Its possible that costal erosion process to envolve a complex of morphogenetic factors like wave action, mechanical, chemical and biological weathering, anthropic action (buildings, deforestation, agriculture, tourism etc.). 

The difference between abrasion and coastal erosion is that the first is a specific kind of process among those of coastal erosion. Actually, abrasion is a mechanical process acting along or at the foot of rocky coast. It is due to the friction between clasts (sand, pebbles) - mainly transported by waves during storm surges and/or intense marine currents - and rocky sea bottom. This process is called "corrasion" and generates the marine abrasion terraces as well as the sea notch widening , in this way contributing to the cliff recession. Corrasion differs from the chemical-physical dissolution that is called "corrosion" (i.e.,the karstic or locally hyper-karst phenomena due to mixing of seawater and freshwater coming from underwater springs ), even if often they act together along a sea cliff.

Coastal erosion: denudation, wind erosion, corrosion, anthropogenetic influence etc.

Abrasion: erosion made only by sea/lake waves.

I just add an interesting point. In eastern European literature on coastal topics, often abrasion is used as synonimuous of coastal erosion, especially when the term in the original language is used. I came across this aspect working in Albania and Montenegro but I am sure it applies to many other countries.

Abrasion is a form of erosion, specifically the scraping of a rock surface by solid particles transported by wind, water, or ice. Other forms of coastal  erosion include chemical weathering and freeze/thaw and sorting cycling.

I agree with the distinction that others have made that the process of abrasion involves the physical scraping of a surface (often rock, but it can also be clay and till) by moving particles – generally sand and gravel. This is in contrast to the direct loosening of material by hydraulic forces or the indirect effects of chemical and biological weathering and removal by those hydraulic forces. It is also worth noting that the effectiveness of abrasion is often enhanced by a reduction in the strength of the material being abraded through physical and chemical weathering. Some work that we have done has shown this for the erosion of till cliffs (Amin and Davidson-Arnott, Canadian Journal of Earth Sciences, 1995) as well as underwater (Davidson-Arnott and Langham, Marine Geology, 1990). Erosion of hard bedrock by abrasion is a slow process and weathering is an important control on how quickly this takes place.

I agree with Robin

Abrasion is a term mainly related to rocky shores. Coastal erosion is a wide concept. More agents are involved in it.

Abrasion, corrasion, bioerosion, biokarst are different kinds of  coastal macro- and micro-processes, often mutually interacting, typical of rocky coast, e.g. sea cliffs. Coastal erosion has a general meaning and includes both rocky and sandy or pebbly beach processes. The latter are characterized by littoral drift due to waves and marine currents (longshore, rip), differently from the rocky coast in which  waves (Mediterranean Basin) and/or tides (oceans) dominate. All these processes (and others) can act along transition environments where rocks and sand/pebbles are present,  e.g. pocket beaches, beaches at the foot of a sea cliff, islet linked to the shoreline by a tombolo, etc. Your doubts could be dispelled reading a good book of Coastal Geomorphology, before specific papers. I suggest the following:

Litorals, beaches, lagoon, reefs, etc.:

1. Robin Davidson-Arnott, 2010.  Introduction to Coastal Processes and Geomorphology, Cambridge University Press, 442 pp.

Sea cliffs, beaches, river mouths, dunes, etc.:

2. Eric Bird, 2008. Coastal Geomorphology. An Introduction. 2nd ed., John Wiley & Sons Ltd, 411 pp.

General topics:

3. Masselink G. & Hughes M.G., 2003), Introduction to Coastal Processes & Geomorphology. Hodder Arnold ed., 354 pp.

Best, Carlo

Actually, abrasion could be caused not by waves, but by sand particles - it may be wind.