There are several other report types that have some resemblance in name or degree of detail to the Phase I Environmental Site Assessment:
Phase II Environmental Site Assessment is an "intrusive" investigation which collects original samples of soil, groundwater or building materials to analyze for quantitative values of various contaminants.  This investigation is normally undertaken when a Phase I ESA determines a likelihood of site contamination.  The most frequent substances tested are petroleum hydrocarbons, heavy metals, pesticides, solvents, asbestos and mold.
Phase III Environmental Site Assessment is an investigation involving remediation of a site. Phase III investigations aim to delineate the physical extent of contamination based on recommendations made in Phase II assessments. Phase III investigations may involve intensive testing, sampling, and monitoring, "fate and transport" studies and other modeling, and the design of feasibility studies for remediation and remedial plans. This study normally involves assessment of alternative cleanup methods, costs and logistics. The associated reportage details the steps taken to perform site cleanup and the follow-up monitoring for residual contaminants.
Limited Phase I Environmental Site Assessment is a truncated Phase I ESA, normally omitting one or more work segments such as the site visit or certain of the file searches. When the field visit component is deleted the study is sometimes called a Transaction Screen.
Environmental Assessment has little to do with the subject of hazardous substance liability, but rather is a study preliminary to an Environmental Impact Statement, which identifies environmental impacts of a land development action and analyzes a broad set of parameters including biodiversity, environmental noise, water pollution, air pollution, traffic, geotechnical risks, visual impacts, public safety issues and also hazardous substance issues.
SBA Phase I Environmental Site Assessment means  properties purchased through the United States Small Business Administration's 504 Fixed Asset Financing Program require specific and often higher due diligence requirements than regular Real Estate transactions. Due diligence requirements are determined according to the NAICS codes associated with the prior business use of the property.  There are 58 specific NAICS codes that require Phase I Investigations.  These include, but are not limited to: Funeral Homes, Dry Cleaners, and Gas Stations. The SBA also requires Phase II Environmental Site Assessment to be performed on any Gas Station that has been in operation for more than 5 years. The additional cost to perform this assessment cannot be included in the amount requested in the loan and adds significant costs to the borrower.
Freddie Mac/Fannie Mae Phase I Environmental Site Assessments are two specialized types of Phase I ESAs that are required when a loan is financed through Freddie Mac or Fannie Mae.  The scopes of work are based on the ASTM E1527-05 Standard but have specific requirements including the following: the percent and scope of the property inspection; requirements for radon testing; asbestos and lead-based paint testing and operations-and-maintenance (O&M) plans to manage the hazards in place; lead in drinking water; and mold inspection.  For condominiums, Fannie Mae requires a Phase I ESA anytime the initial underwriting analysis indicates environmental concerns.
HUD Phase I Environmental Site Assessment
The U.S. Department of Housing and Urban Development also requires a Phase I ESA for any condominium under construction that wishes to offer an FHA insured loan to potential buyers.