Securitized vs Unsecuritized.   First off what are common to both?

In a nut shell:

What's common:

Tenants in Common is a form of ownership in real property that typically are large commercial properties that are professionally managed.  They can also be small forms of Tenants in Common purchased by families/friends/investment groups.  But for the purpose of this summary, we focus on the large commerical type of property. 

You have an ownership interested held as a Tenant in Common with other owners.  The majority decides when to liquidate the property.  You can sell at anytime your interest, although there typically is no readily secondary market for your share.  Your interest would be offered to the existing Tenants or to the Sponsor.  There is a monthly return on your investment as disclosed in the offering.  You can claim real estate deductions on your tax returns(check with your Accountant for specifics).  There is professional property management for the property and typically it is a class A commercial property with a triple net lease type of arrangement with the tenants. Typically there is an existing nonrecourse loan against the property. 

You can tax defer your gain on the sale of your TIC investment by rolling it(1031) over into another TIC or go on your own and buy another piece of real estate.  TIC purchase price can range from $25,000 to $1,000,000+, depending upon the property, how many investors each TIC can have and whether it is bought as a securitized or unsecuritized TIC.  Typical hold period is 5-7 years.  Typical returns are anywhere from 6%-8% depending upon the property.

What's different: 

Securitized:

Tenants In Common(TIC)  ownership interest in real estate properties have been reviewed by the Securities Exchange Commission and approved for sales through Security dealers to the general public.  These properties must adhere to the rules and regulations of the SEC.   Since it is a security, if purchased and held in an IRA, then the proceeds goes back into your IRA as tax deferred. If bought outside of an IRA, then any profits are taxed as capital gains tax.  Again, check with your CPA/Accountant for tax implications.

Unsecuritized:

TIC properties that have not gone through the SEC process and thus do not have to adhere to those rules and regulations to the general public.  These ownership interests are typically sold through the sales arm of the Real Estate brokerage that purchased the properties and package them as TIC. Since it is considered Real Estate, then it will fall under the IRS 1031 regulations and when you sell, you will have to consider whether to tax defer the gains into another like kind property or "cash out" and pay the gain tax.  Check with your CPA/Accountant for tax implications.