What is the difference between Founder effect and Bottleneck effect?
Genetic drift is an EVOLUTIONARY PROCESS

Source: Wikipedia > Genetic Drift


  Genetic drift (also known as allelic drift or the Sewall Wright effect2 after biologist Sewall Wright) is the change in the frequency of a gene variant (allele) in a population due to random sampling of organisms.


I think that these terms are used without a perfect semantic. An obvious case 

A population bottleneck is a DEMOGRAPHIC EVENT

Source: Wikipedia > Population Bottleneck


  A population bottleneck [..] is a sharp reduction in the size of a population due to environmental events (such as earthquakes, floods, fires, disease, or droughts) or human activities (such as genocide)


A founder effect is an EVOLUTIONARY PROCESS THAT RESULTS FROM A FOUNDING EVENT

Source: Provine 2004


  The “founder” principle, as introduced by Mayr in 1942, was an auxiliary mechanism (less important than random drift) for producing reduced variability in an isolated population started by a few individuals or even by a single fertilized female. Mayr saw a distinction between the “founder” effect and random drift. The founders were not a random sampling of the main population, but, once isolated as a small population, would undergo random drift


In other words, a founder effect does NOT refer to the ppulation bottleneck causing by a founding event. A founder effect refers to the increase in genetic drift (loss of genetic diversity is expected) caused by a founding event. A founding event is the event by which few individuals (eventually only one) quit a large population to settle down a new small populations. As such, a founder event is a type of population bottleneck. I think that one could further extrapolate the term "founder effect" to any increase in genetic drift caused by a population bottleneck.

Do all authors use the same definitions?

I have not done a good literature review to answer this question but I would not be surprised if different authors, use slightly different definitions.

For example, some authors (e.g. Peery at al 2012, Raymond and O'Brien 1993, Duarte et al. 1992) have used the term "genetic bottleneck" instead of "population bottleneck". Wikipedia indicates that these two terms are synonyms. However I could not find any paper that formally define the term genetic bottleneck but all the papers using this term seem to be specifically interested into the genetic signature of population bottleneck. As such, the semantic relationship between population bottleneck and genetic bottleneck could be the same as between founding event and founder effect. Genetic bottleneck could be defined as the increase of genetic drift that is caused by population bottleneck.